September 2023 Selected Climate Anomalies and Events Map

Temperature

Coinciding with the release of the January 2023 Global Climate Report, the NOAA Global Surface Temperature (NOAAGlobalTemp) dataset version 5.1.0 replaced version 5.0.0. This new version includes complete global coverage and an extension of the data record back in time an additional 30 years to January 1850. While anomalies and ranks might differ slightly from what was reported previously, the main conclusions regarding global climate change are very similar to the previous version. Please see our Commonly Asked Questions Document and web story for additional information.

NOAA's National Centers for Environmental Information calculates the global temperature anomaly every month based on preliminary data generated from authoritative datasets of temperature observations from around the globe. The major dataset, NOAAGlobalTemp version 5.1.0, updated in 2023, uses comprehensive data collections of increased global area coverage over both land and ocean surfaces. NOAAGlobalTempv5.1.0 is a reconstructed dataset, meaning that the entire period of record is recalculated each month with new data. Based on those new calculations, the new historical data can bring about updates to previously reported values. These factors, together, mean that calculations from the past may be superseded by the most recent data and can affect the numbers reported in the monthly climate reports. The most current reconstruction analysis is always considered the most representative and precise of the climate system, and it is publicly available through Climate at a Glance.


September 2023

The September global surface temperature was 1.44°C (2.59°F) above the 20th-century average of 15.0°C (59.0°F), making it the warmest September on record. September 2023 marked the 49th-consecutive September and the 535th-consecutive month with temperatures at least nominally above the 20th-century average. September 2023 was 0.46°C (0.83°F) above the previous record from September 2020, and marks the largest positive monthly global temperature anomaly of any month on record. The September 2023 global temperature anomaly surpassed the previous record-high monthly anomaly from March 2016 by 0.09°C (0.16°F). The past ten Septembers (2014–2023) have been the warmest Septembers on record.

For the sixth consecutive month, September saw a record-high monthly global ocean surface temperature. September 2023 tied August 2023 for the highest monthly sea surface temperature anomaly (+1.03°C or +1.85°F) of any month in NOAA's 174-year record. El Niño conditions that emerged in June continued into September, and according to NOAA's Climate Prediction Center there is a greater than 95% chance that El Niño will continue through the Northern Hemisphere winter (January–March 2024).

Temperatures were above average throughout most of North America, South America, Europe, Africa, Asia, Oceania and Antarctica. Parts of Europe, southern and north-central North America, northern and central South America, western and eastern Africa, southwestern and central eastern Asia, southwestern Oceania and Antarctica experienced record-warm temperatures this month. Sea surface temperatures were above average across much of the northern, western and southwestern Pacific as well as the Atlantic and the Indian Ocean. Record-warm temperatures covered 20% of the world's surface this September, which was the highest percentage of any month since the start of records in 1951.

Temperatures were near to cooler than average across parts of southern South America and central Russia. Sea surface temperatures were near to below average over parts of the southeastern Pacific Ocean. Less than 1% of the world's surface had a record-cold September.

A smoothed map of blended land and sea surface temperature anomalies is also available.

North America, South America, Africa, and Europe each had their warmest September on record. South America had a September that was 2.48°C (4.46°F) above the 20th century average, which was its highest monthly temperature departure from average of any month on record.

  • The contiguous U.S. had its seventh-warmest September in the 129-year record. More than 100 U.S. counties had their warmest September on record.
  • September in Peru ranked warmest on record.
  • Denmark had its warmest September on record, and in an unusual occurrence, September was actually warmer than both July and August.
  • Austria had its warmest September in the 257-year record.
  • Switzerland recorded its warmest September on record.
  • September in Germany also ranked warmest on record.
  • Latvia also had its warmest September on record.
  • At 2.2°C above the 1991–2020 average, September 2023 in the United Kingdom tied September 2006 as the warmest on record. England and Wales each had their warmest September on record.
  • The Netherlands had its second-warmest September since 1901.
  • Italy had its third-warmest September on record.

Asia had its second-warmest September.

  • September in Japan ranked warmest on record.
  • Hong Kong experienced 10 consecutive "very hot days", the longest streak of such weather in the region during September.
  • Pakistan had its fourth-warmest September on record.
  • September in Turkey ranked sixth warmest on record.

September in Oceania ranked third warmest on record.

September Ranks and Records
SeptemberAnomalyRank
(out of 174 years)
Records
°C°FYear(s)°C°F
Global
Land+2.34+4.21Warmest1st2023+2.34+4.21
Coolest174th1912-0.79-1.42
Ocean+1.03+1.85Warmest1st2023+1.03+1.85
Coolest174th1904-0.46-0.83
Land and Ocean+1.44+2.59Warmest1st2023+1.44+2.59
Coolest174th1912-0.52-0.94
Northern Hemisphere
Land+2.16+3.89Warmest1st2023+2.16+3.89
Coolest174th1912-0.99-1.78
Ocean+1.41+2.54Warmest1st2023+1.41+2.54
Coolest174th1912-0.57-1.03
Land and Ocean+1.73+3.11Warmest1st2023+1.73+3.11
Coolest174th1912-0.75-1.35
Southern Hemisphere
Land+2.76+4.97Warmest1st2023+2.76+4.97
Coolest174th1986-1.28-2.30
Ocean+0.77+1.39Warmest1st2023+0.77+1.39
Coolest174th1903-0.42-0.76
Land and Ocean+1.15+2.07Warmest1st2023+1.15+2.07
Coolest174th1904-0.39-0.70
Antarctic
Land and Ocean+2.07+3.73Warmest1st2023+2.07+3.73
Coolest174th1986-2.06-3.71
Arctic
Land and Ocean+2.30+4.14Warmest2nd2016+2.36+4.25
Coolest173rd1881-1.45-2.61

500 mb maps

In the atmosphere, 500-millibar height pressure anomalies correlate well with temperatures at the Earth's surface. The average position of the upper-level ridges of high pressure and troughs of low pressure—depicted by positive and negative 500-millibar height anomalies on the map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

hgtanomaly-global-202309.png

Year-to-date Temperature: January–September 2023

The January–September global surface temperature ranked highest in the 174-year record at 1.10°C (1.98°F) above the 1901–2000 average of 14.1°C (57.5°F). This surpassed the previous record from January–September 2016 by 0.03°C (0.05°F). According to NCEI's statistical analysis and data through September, there is a greater than 99% chance that 2023 will rank as the warmest year on record.

South America and Europe had their warmest year-to-date periods, while it was Africa's second-warmest such period on record. Asia had its fourth-warmest January–September period, and North America had its fifth-warmest such period. January–September 2023 ranked 12th warmest on record for Oceania.

A smoothed map of blended land and sea surface temperature anomalies is also available.

January to September was characterized by warmer-than-average conditions across much of eastern, southern, and northern North America, South America, Europe, Africa, the Arctic, Oceania, and Asia. Sea surface temperatures were above-average throughout most of the northern, western, and subtropical eastern Pacific, Atlantic, and Indian Oceans. The Southern Hemisphere had its warmest year-to-date period, while the Northern Hemisphere had its second-warmest such period. The Arctic had its sixth-warmest January–September period on record.

Temperatures were near or below average across parts of western North America and western Alaska, Greenland, and Antarctica. Sea surface temperatures were near to below average across parts of the southeastern and central-east Pacific and northern Atlantic Oceans.

January–September Ranks and Records
January–SeptemberAnomalyRank
(out of 174 years)
Records
°C°FYear(s)°C°F
Global
Land+1.61+2.90Warmest3rd2016+1.70+3.06
Coolest172nd1885-0.75-1.35
Ocean+0.87+1.57Warmest1st2023+0.87+1.57
Coolest174th1904-0.47-0.85
Land and Ocean+1.10+1.98Warmest1st2023+1.10+1.98
Coolest174th1911-0.48-0.86
Northern Hemisphere
Land+1.85+3.33Warmest3rd2016+2.06+3.71
Coolest172nd1885-0.86-1.55
Ocean+1.04+1.87Warmest1st2023+1.04+1.87
Coolest174th1904-0.52-0.94
Land and Ocean+1.39+2.50Warmest2nd2016+1.40+2.52
Coolest173rd1917-0.55-0.99
Southern Hemisphere
Land+1.05+1.89Warmest3rd2020+1.10+1.98
Coolest172nd1917-0.67-1.21
Ocean+0.75+1.35Warmest1st2023+0.75+1.35
Coolest174th1911-0.45-0.81
Land and Ocean+0.81+1.46Warmest1st2023+0.81+1.46
Coolest174th1911-0.44-0.79
Antarctic
Land and Ocean+0.23+0.41Warmest30th2007+0.78+1.40
Coolest145th1962-0.60-1.08
Ties: 1978
Arctic
Land and Ocean+2.08+3.74Warmest6th2016+2.88+5.18
Coolest169th1966-1.18-2.12

Precipitation

The maps shown below represent precipitation percent of normal (left, using a base period of 1961–1990) and precipitation percentiles (right, using the period of record) based on the GHCN dataset of land surface stations.

September 2023

Above-average September precipitation was observed across parts of southern Asia, southern Russia, the northeastern and western U.S., and New Zealand. Meanwhile, drier-than-average conditions were present across much of Australia, Indonesia, and across parts of Europe, northern South America, and southern and central-eastern North America.

Global Precipitation Climatology Project (GPCP)

The following analysis is based upon the Global Precipitation Climatology Project (GPCP) Interim Climate Data Record. It is provided courtesy of the GPCP Principal Investigator team at the University of Maryland.

September Highlights:
  • The ongoing El Niño dominated the rainfall anomaly patterns from the eastern Indian Ocean, across the tropical Pacific, and into Central America and northern South America.
  • The South Asian Monsoon was wetter than average over land, and drier to the south over the ocean, intertwined with the ENSO pattern.
  • The European drought continued, but floods in Greece and Libya were tied to a warm Mediterranean and a tropical-like circulation.
  • The rainfall intensity of the global Intertropical Convergence Zone (ITCZ) set a record for September due to global warming and the current El Niño.

The precipitation pattern across the globe for this September (Fig. 1, top panel) had a very strong ITCZ across the Pacific and the typical Asian Monsoon distribution of strong rains across the Indian sub-continent eastward across Indochina and southern China. In the Atlantic (and the western Pacific), one can see fingers of rainfall associated with tropical cyclone tracks. These storm track effects can be seen even better in the anomaly maps in the middle and bottom panels of the same figure as relatively narrow, mostly north-south oriented wetter-than-normal zones associated with individual storms.

The anomaly maps also show that the Asian Monsoon across South Asia was wetter than normal from India eastward. These rainier-than-average areas were associated with flooding, often related to tropical cyclones, or even just remnants of these storms, moving through the areas. This was especially felt this month with flooding in various areas along the South China coast, including Hong Kong. Immediately south of the positive monsoon anomaly lies a strong east-west negative anomaly centered just to the south of the equator. This couplet expressed the rainfall effect of the close-in north-south monsoon circulation for this month. A broader rainfall deficit extended over much of the South Indian Ocean and Australia and that represents the large-scale descent zone (apparently also stronger than normal) this September.

Although the mean global surface temperature for this September made another record at the high end, unlike the last few months, the global precipitation total this month was closer to the climatological mean than a record-high value. However, overlain onto the global means and patterns was the effect of the ongoing El Niño, whose Niño 3.4 SST index increased again this month to +1.6 C. Figure 2 shows the El Niño composite for September (top panel) and repeats the anomaly map for this September (bottom panel). This September's positive anomaly along the Pacific ITCZ fits the composite very well, as does the negative anomaly across and west of Sumatra. The El Niño and Asian Summer Monsoon rainfall patterns are certainly intertwined. However, the anomalies across the South Asia land areas do not fit the ENSO composite. The negative anomaly over northern South America in the El Niño composite was also evident in this month's numbers, although the negative anomalies this month cover much of the continent, not just the north. An exception to this pattern was the very intense feature in southern Brazil (with associated floods) that extended southeastward into the Atlantic. The drier-than-normal feature over central America also matched, but the "expected" pattern from the composite does not match this month's reality over Mexico and North America. Overall, as the El Niño has intensified over the past six months (e.g., increasing Niño 3.4 SST index), the pattern correlation between the El Niño anomaly composite and this month's anomaly pattern has also continued to increase to +0.39 this month, although the agreement between the two patterns is confined to the tropics between the eastern Indian Ocean and northern South America.

Elsewhere, across North America dry conditions existed across most of the U.S. and Canada (wildfires continued to burn in western Canada), but with above average rainfall across the northwest U.S. and Alaska. Drought continued in Hawaii, as it did across the southern tier of mainland states, centered in Louisiana. However, right along the east coast, tropical systems, or remnants thereof, produced above-average rainfall in Newfoundland/Nova Scotia (post-tropical Hurricane Lee) and floods in North Carolina and heavy rain farther north (Tropical Storm Ophelia). And then Ophelia's remaining circulation looped around and produced intense floods in New York City and surrounding areas. The positive anomaly pattern just off the North American east coast gives the best evidence for these occurrences, even though on a larger scale of the analysis (2.5° latitude-longitude, monthly) drier conditions dominated.

In Europe, dry conditions dominated a large swath across France to the northeast and into Asia, helping to continue Europe's drought. But, to the southwest, Spain was hit with a tropical-like depression from the Atlantic with some daily rain amounts over 200 mm and associated flooding, which helped produce a positive anomaly for the month for the Iberian peninsula. The eastern Mediterranean also shows a positive anomaly over the water and some surrounding land areas. A major contributor to this feature was "Daniel", a so-called Medicane (a Mediterranean tropical-cyclone-type storm) that formed over the very warm Mediterranean, hit Greece causing very serious floods (and also flooding in Bulgaria and Turkey). Afterwards, Daniel's circulation crossed back over the Mediterranean to the south and hit eastern Libya causing heavy rain, flooding, and dam failures and leading to the tragic loss of 5000 lives in the city of Derna.

Taking a look at a larger scale, as noted earlier, the Pacific ITCZ was very intense this September. This intensity extended to a global scale where Fig. 3 shows the anomaly of the peak intensity of that tropical rainfall feature (over both ocean and land) averaged over all longitudes for each September since 1979. A long-term trend in this measure of intensity is evident with large inter-annual variations (often related to ENSO). The long-term trend associated with global warming is augmented by this month's El Niño conditions to produce a "record" value for this September 2023. One can also note the relative minima for 2021 and 2022 when La Niña conditions were present. These types of statistics convey the interplay between global warming and ENSO effects on rainfall intensity on the climate scale.

Drought in September 2023

Drought information is based on global drought indicators available at the Global Drought Information System website, and media reports summarized by the National Drought Mitigation Center.

September Highlights:
  • Beneficial precipitation fell across some of the world's drought areas during September 2023, but dry and hot conditions dominated the continents.
  • It was a record-warm September for Europe, Africa, North America, and South America, with Asia having the second warmest September and Australia the third warmest. For many continents, record heat extended back several months, increasing evapotranspiration which exacerbated drought in the dry areas and, in some cases, countering beneficial precipitation.
  • It continued dry over drought-plagued parts of the Americas, Africa, Australia, the Indian subcontinent, Europe, and western Russia.
  • As noted by the University of Maryland, the ongoing El Niño dominates the rainfall anomaly patterns over many of the dry areas—from the eastern Indian Ocean, across the tropical Pacific and into Central America and northern South America.
  • A significant portion of the world's agricultural lands was still suffering from low soil moisture and groundwater levels, and satellite observations showed stressed vegetation on all continents.
  • The GEOGLAM Crop Monitor indicated that agriculture was most threatened in parts of the Americas, East Africa, southern Asia, and parts of Australia.
  • The Famine Early Warning System Network (FEWSNet) revealed significant food insecurity continuing in parts of Central and South America, Southwest Asia, and much of Africa.

Most of Europe was drier than normal during September 2023, with only the Iberian Peninsula, British Isles, and Scandinavia wetter than normal. Temperatures were warmer than normal across the continent, making September 2023 the warmest September, continent-wide, in the 1910-2023 NOAA/NCEI record. The warm anomalies have been persistent throughout the summer, giving Europe the warmest August-September, July-September, and June-September. The excessive heat has increased evapotranspiration, making drought conditions worse. The Standardized Precipitation Evapotranspiration Index (SPEI) integrates the effect of precipitation and temperature. The SPEI shows that much of southern and eastern Europe has been dry for the last 2 to 3 months, with most of the continent from the Iberian Peninsula to the Baltic Sea drier than normal at time periods from 6 months to the last 4 years. Soils continued dry from Portugal to northern Europe, with the satellite-based (GRACE) indicator of groundwater revealing low groundwater across most of Europe. Satellite observations of vegetative health (Vegetative Health Index, VHI) revealed stressed vegetation over parts of France, the British Isles, and Scandinavia. The European Combined Drought Indicator showed some level of drought from France to Eastern Europe and Scandinavia, with 30.5% of the EU-27 territory in Drought Watch, Warning, or Alert conditions, which is more than last month.

According to media reports, Spain's food and drink industry made a rare call for the government to grant it priority access to water amid a drought that's threatening food supplies in the southern European country. The two-year drought and record heat have cut Spain's olive crop in half—doubling olive oil prices; climate change is expected to continue to drive prices up. The skyrocketing olive oil prices have led to a spate of thefts of bulk olive oil in the country. The Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) noted that, due to below-average early summer precipitation, trees were turning brown earlier in the Jura mountains and on the western side of the Central Plateau.

September was drier than normal across large swaths of Asia, from western Russia to central Asia and from Southwest Asia to parts of China. Much of the continent was warmer than normal, with September 2023 ranking as the second warmest September in the NOAA/NCEI record. The anomalous warmth increased evapotranspiration across much of Asia, especially in Russia and northern China, according to the Evaporative Stress Index (ESI). Excessive warmth characterized much of the summer, with the last 2 to 4 months ranking as the warmest such periods on record, continent-wide. According to the SPEI, drought plagued Southwest Asia and parts of India, Russia, Southeast Asia, and northern China at every time scale from the last 2 months to 4 years. The lack of precipitation and high evaporation dried soils in these areas, as seen on satellite-based products (GRACE), and groundwater levels were significantly lowered (GRACE). Satellite observations (VHI) revealed poor vegetative health from Southwest Asia to northern China and Mongolia. Drought conditions were confirmed over northern, eastern, and coastal southwestern parts of India on the India Drought Monitor, covering about 21.6% of the nation, which is about the same as last month. Some short- or long-term drought was indicated on some of the islands in the Southwest Pacific on the NIWA Island Climate Update maps, with more extensive drought at the longer time periods.

According to media reports (Radio Free Europe), hot, dry weather in southern Kazakhstan has ruined crops, limited pasture and the production of animal fodder as irrigation supplies dwindled; some were opting to slaughter livestock for lack of affordable animal feed. Reuters reported that, in Turkey, cattle now graze and sunflowers grow in the dried lakebed of the Terkos Dam outside Istanbul, where a drought this year has reduced water levels in the reservoirs of Turkey's largest city to their lowest in nearly a decade. "In the 11 months to September, Turkey's northwest received 23% less precipitation than average, according to the Turkish State Meteorological Service. In August alone, it was 74% lower than average, and down 90% from last year." The Daily Sabah added that, with the impending drought crisis threatening Istanbul's water supply throughout the fall and winter, preparations are now underway to extract water from the depths of dams. The Hindu media organization reported that, in view of drought and distress caused to the farming community in Karnataka, in southwestern India, the State Government has decided to scale down this year's Dasara celebrations. The 10-day-long Dasara festival is the showpiece event in the cultural calendar of Karnataka.

September continued dry across much of the Mediterranean coast (the Maghreb region) of Africa, as well as northwest, eastern (Horn of Africa), western equatorial, and southeast parts of the continent. Most of the continent was warmer than normal, with September 2023 ranking as the warmest September continent-wide in the 1910-2023 NOAA/NCEI record; record heat continent-wide extended over the last 8 months (February-September), with the year to date being the second warmest January-September. The excessive warmth increased evapotranspiration, as seen on the ESI. The SPEI revealed dryness in these northern, eastern, and southern areas, with the area expanding as the time scales lengthened. Satellite (GRACE) observations revealed persistent low soil moisture and groundwater in the Maghreb and adjacent northern regions, over parts of the Horn of Africa, and parts of central to southern Africa, with the worst conditions in the north and east. Satellite observations of vegetative health (VHI) revealed stressed vegetation over the Maghreb region and much of the Horn of Africa, and southern Africa. An analysis by the African Flood and Drought Monitor estimated 22% of the continent in drought at the end of September, which is about the same as last month.

According to state media reports, Morocco's importation of live animals intended for consumption has surged fivefold since the start of the year, as the nation seeks to stabilize meat prices and ensure a steady supply in preparation for Eid al-Adha, the annual festival of sacrifice. The Associated Press reported that France is sending military forces to distribute water on the French Indian Ocean territory of Mayotte, off the southeastern Africa coast, which is facing an unprecedented water crisis prompted by the island cluster's most severe drought in decades. Reuters noted that maintenance issues and climate change-induced water shortages have caused a 400-megawatt electricity shortfall in Tanzania, triggering power rationing across the East African nation; reduced water levels at hydropower dams contributed to the shortfall.

Like last month, most of Australia was drier than normal during September 2023, with unusually hot temperatures. According to the Australian Bureau of Meteorology, the continent had the driest and third warmest September on record. Temperature records began in 1910, and precipitation records began in 1900. The hot temperatures increased evapotranspiration, especially in the western and eastern areas, as seen on the ESI map. The SPEI showed dry conditions across the continent, except in the north-central region, for the last 1 to 9 months. Normal to wet conditions dominate at 12 to 36 months, with dryness from the west to northeast at 48 months. Dry soils stretched from the west coast to east coast, with wet soils in the north and southeast, according to GRACE soil moisture data. The GRACE data showed low groundwater in the west and east. These anomaly patterns were confirmed by Australian Bureau of Meteorology and Australian Combined Drought Indicator analyses, which also showed low streamflows along the west and east coasts and some areas on both coasts with low water storage levels. According to media reports (Australian Broadcasting Corporation), Australia's Bureau of Meteorology has declared two major climate drivers are officially underway — El Niño and a "positive" Indian Ocean Dipole — prompting further warnings that extreme heat could hit this spring and summer. These two climate drivers are linked to hot, dry conditions across the continent.

In South America, September was drier than normal in northern and western regions, with wetter-than-normal conditions in parts of the south. Virtually the entire continent was much warmer than normal, with only southern parts of Argentina and Chile near to cooler than normal. This resulted in the warmest September in the NOAA/NCEI record, continent-wide. Record continental warmth extended back through the last 12 months (October-September). The unusual warmth increased evapotranspiration, as indicated on the ESI map, which exacerbated drought conditions. The SPEI revealed extensive and widespread drought from northern Argentina and Chile to the northern coast of South America at 1- to 6-month time scales. The dry area crept southward at longer time scales out to 48 months, with some pockets of wetness appearing in the north. Satellite (GRACE) observations revealed extensive areas of low groundwater and soil moisture from Venezuela to Brazil and southern Peru to the southern tip of the continent. Satellite analysis revealed poor vegetative health from Colombia to Brazil and Peru to Argentina. Drought was confirmed in Brazil on the Brazilian Drought Monitor, in Bolivia on the Bolivian Drought Monitor, in Chile and Argentina on Southern South America Drought Information System and Chilean Combined Drought Index maps, and in western South America countries on the Western South America Regional Drought Monitor.

According to media reports (BNAmericas), a wave of water emergencies has hit Bolivia as the drought worsens — 71 municipalities had declared water emergencies or disasters by September 21 — prompting the central government to prepare to step up relief efforts. The Associated Press reported that the Amazon rainforest in Brazil is facing a severe drought that may affect around 500,000 people by the end of the year: "Many are already struggling to access essential supplies such as food and water, because the principal means of transportation in the region is waterways, and river levels are historically low. Droughts also impact fishing, a means of subsistence for many riverside communities." Reuters added, Brazil's government is preparing a task force to provide emergency assistance to inhabitants in the Amazon region hit by a severe drought that has impacted the rivers that are their life support. Environment Minister Marina Silva said, "Low river levels and hotter waters have killed masses of fish seen floating on river surfaces, contaminating the drinking water."

In North America, September was drier than normal across most of Canada, Mexico, and Central America, and from the southwestern U.S. to the Great Lakes. Temperatures were warmer than normal across most of the continent, except for Alaska, southwest Canada, and the U.S. West Coast. Continent-wide, September 2023 ranked as the warmest September in the NOAA/NCEI record. As seen on the ESI map, the intense heat increased evapotranspiration from Canada to Mexico, exacerbating drought conditions. The abnormally hot temperatures for the summer and part of the spring resulted in record hot temperatures continent-wide for the last 6 months (April-September). The SPEI indicated that intense dryness dominated Canada, Mexico, Central America, and the southern U.S. for the last 1 to 48 months. In the U.S., the Mississippi Valley and parts of the Great Plains were dry at 1- to 12-month time scales, the Plains were dry at 24 months, and Plains to West Coast were dry at 36- to 48-month time scales. According to national analyses, the U.S. had the seventh warmest and 22nd driest September in the 1895-2023 record, and Mexico had the driest and warmest September in the national record that begins in 1941; moderate to exceptional drought covered 75.0% of Mexico and 40.1% of the contiguous U.S. (33.6% of the 50 States and Puerto Rico), and abnormal dryness and drought affected 72% of Canada. Hundreds of large wildfires occurred in all three countries during September. Satellite (GRACE) observations revealed extensive areas of low groundwater and soil moisture across most of Canada, Mexico, and Central America, and across parts of the southern and central U.S. Satellite analysis indicated poor vegetative health across most of the continent, except in parts of the U.S. The North American Drought Monitor product depicted drought across the U.S. Pacific Northwest to much of western to central Canada, with abnormal dryness or drought even extending to Labrador on the eastern Canadian coast; drought stretched across the length of Mexico and into the southern U.S., with abnormal dryness or drought extending along the Mississippi and Ohio Valleys and into the central Plains. The Caribbean Regional Climate Center SPI maps showed areas of short-term (1 to 6 months) or long-term (12 to 24 months) dryness across parts of the Caribbean islands.

In Canada, the AAFC (Agriculture and AgriFood Canada) reported that abnormally dry to drought conditions affected 69% of the country's agricultural landscape. U.S. Department of Agriculture (USDA) statistics indicated that 55% of the nation's topsoil moisture and 60% of the subsoil moisture were short or very short (dry or very dry) at the end of September, and 18% of the nation's corn crop, 17% of the soybean crop, 43% of the cotton crop, and 35% of the nation's pasture and rangeland were in poor to very poor condition. Mexico's CONAGUA agency reported the nation's reservoir storage 34% of average, with 122 of the 210 main dams in the country having a storage of less than 50%. The National Forestry Commission (CONAFOR) reported that, from January 1 to September 28, 2023, fires have burned a total of 924,549.34 hectares in Mexico; this figure is second only to the similar period in 2011, when 952,316.10 hectares burned.

According to media reports (Grain Central), persistent hot and dry weather conditions across the Prairie provinces is expected to reduce the production of Canada's wheat, barley, oats, and canola crops, while corn and soybean output is expected to increase year-on-year as eastern Canada has enjoyed higher-than-average rainfall since the beginning of the growing season. Reuters reported that the Panama Canal threatened to further reduce the maximum amount of vessel transits authorized per day if a drought that has hit the waterway this year continues. Phys.org added that the drought has prompted Panama to look into new sources of water for the Panama Canal (the Panama Canal moves six percent of global maritime trade in a normal year). According to the U.S. Army Corps of Engineers, water levels on the Mississippi River have fallen to near record levels a full month ahead of last year's low water stage. The Mississippi River has fallen 15 feet in a month. The low level of the Mississippi River has forced barge companies to lighten loads, making it more costly to transport grain and other goods on the river; the cargo rate from St. Louis downriver was up 77% above the three-year average. Nation News Barbados reported that the Barbados-based Caribbean Climate Outlook Forum (CariCOF) said, as of September, severe, or worse, short-term drought has developed in Grand Cayman, French Guiana, northern Guyana, eastern Suriname, Tobago, and the US Virgin Islands. Long-term drought to the end of November is evolving in western Belize, Dominica, southern French Guiana, Martinique, south east Puerto Rico, St Vincent, Trinidad and Tobago, and might possibly develop or continue in Aruba, Bonnaire and Curacao, Barbados, French Guiana, Grenada, St Lucia and St Maarten/St-Martin. CariCOF said short-term drought to the end of December, is evolving in central and southern French Guiana, Suriname, Trinidad, and might possibly develop in Dominica, Guyana, Martinique, St Lucia, St Vincent and northern French Guiana.


Ocean Heat Content

Ocean Heat Content (OHC) is essential for understanding and modeling global climate since > 90% of excess heat in the Earth's system is absorbed by the ocean. Further, expansion due to increased ocean heat contributes to sea level rise. Change in OHC is calculated from the difference of observed temperature profiles from the long-term mean.

July–September 2023 Ocean Heat Content (1022 joules)
Basin0-700 meters | Rank (1955-2023)
Entire BasinNorthern HemisphereSouthern Hemisphere
Atlantic8.2541st4.9702nd3.2851st
Indian4.1831st0.7097th3.4741st
Pacific7.6441st3.6681st3.9762nd
World20.0821st9.3471st10.7351st
Source: Basin time series of heat content
July–September 2023 Heat Content 0-700 m
Heat Content 0-700 m

Global OHC for July–September 2023 is the highest July–September OHC in our records, which extend back to 1955. Overall, the latest quarterly OHC reveals widespread warmer than normal conditions relative to the 1955–2006 mean, a situation observed since the end of 2016. The July–September 2023 OHC shows large scale features similar to those observed in the previous quarter. Notable differences relative to April–June 2023 are observed in the tropical Pacific Ocean: while there was a meridional expansion of the higher than normal conditions, > 10x105 J/m3, extending from the coast of South America to about 150°W, OHC is lower in the tropical western Pacific Ocean. Much higher, > 30x105 J/m3, than normal OHC conditions continue to exist at mid-latitudes in the central and western Pacific Ocean, as well as in the Gulf of Mexico and Caribbean Sea, the Gulf Stream/North Atlantic Current, and the northern Antarctic Circumpolar Current in the Indian Ocean sector. Higher, > 10x105 J/m3, than normal OHC conditions dominate the subtropical South Indian Ocean, the Tasman Sea, and most of the South Atlantic Ocean. Cool conditions, < -10x105 J/m3, appear in the western subtropical North Pacific Ocean, while the cool feature observed since early 2020 in the subpolar North Atlantic Ocean south of Greenland has decreased in size and strength.

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Citing This Report

NOAA National Centers for Environmental Information, Monthly Global Climate Report for September 2023, published online October 2023, retrieved on June 24, 2024 from https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202309.