September 2018 Global Climate Report

September 2018 Selected Climate
Anomalies and Events Map

Introduction

Temperature anomalies and percentiles are shown on the gridded maps below. The anomaly map on the left is a product of a merged land surface temperature (Global Historical Climatology Network, GHCN) and sea surface temperature (ERSST.v4) anomaly analysis as described in Huang et al. (2016). Temperature anomalies for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCEI's Global Surface Temperature Anomalies page. The percentile map on the right provides additional information by placing the temperature anomaly observed for a specific place and time period into historical perspective, showing how the most current month, season or year compares with the past.

Temperatures

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 September 2018 map—is generally reflected by areas of positive and negative temperature anomalies, respectively, at the surface.

September

September 2018 Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

September 2018 Blended Land and Sea Surface
Temperature Percentiles

During September 2018, much of the global land and ocean surfaces had warmer- to much-warmer-than-average conditions. The most notable warm temperatures were present across southern South America, Alaska, the southwestern and eastern contiguous U.S., much of Europe, the Middle East, as well as western and eastern Russia, where temperature departures from average were +2.0 (+3.6°F) or higher. Record warm temperatures were present across parts of western Alaska and its surrounding ocean, Far East Russia, the Barents Sea, as well as across parts of the Atlantic Ocean, southern South America, western Indian Ocean, Europe, and the Middle East. Cooler-than-average conditions were present across much of Canada, Mongolia, northern China, and across parts of eastern Indian Ocean, and the northern Atlantic Ocean (south of Greenland) as well as eastern parts of the Atlantic Ocean. The most notable cool temperature departures from average during September were in central and western Canada, where temperatures were 3.0°C (5.4°F) below average or less. Record cold September temperatures were observed in southwestern Canada.

With global records dating back to 1880, the September 2018 global temperature across the world's land and ocean surfaces was 0.78°C (1.40°F) above the 20th century average of 15.0°C (59.0°F)—tying with 2017 as the fourth highest September temperature in the 139-year record. The ten warmest September global land and ocean surface temperatures have occurred since 2003, with the last five years (2014–2018) comprising the five warmest Septembers on record. September 2015 is the record warmest September at +0.93°C (+1.67°F). September 2018 also marks the 42nd consecutive September and the 405th consecutive month with temperatures, at least nominally, above the 20th century average.

The globally-averaged land surface temperature during September 2018 was 1.02°C (1.84°F) above the 20th century average of 12.0°C (53.6°F) and the sixth highest September global land temperature since global records began in 1880. The ten warmest September global land temperatures have occurred since 2005, with 2016 the record warmest September global land temperature at +1.24°C (+2.23°F). The global oceans had a September temperature that ranked as the fourth highest in the 139-year record at 0.69°C (1.24°F) above the 20th century average of 16.2°C (61.1°F). The ten warmest global ocean September temperatures have occurred since 2003, with the last five years (2014–2018) comprising the five warmest Septembers on record.

According to NCEI's Regional Analysis, four of six continents had a September temperature that ranked among the four warmest Septembers on record, with Europe having its warmest September on record at +2.02°C (+3.64°F). This value surpassed the previous record set in 2016 by more than 0.11°C (0.20°F). September 2018 marks the first time since continental records began that Europe had a September temperature departure that was +2.0°C (+3.6°F) or higher. South America had its second warmest September on record at +1.51°C (+2.72°F), falling behind the record set in 2015 by 0.13°C (0.23°F). Africa and Asia had their third and fourth warmest Septembers, respectively. Meanwhile, North America had its smallest September temperature departure from average for September in 10 years (since 2008) at 0.27°C (0.49°F).

Select national information is highlighted below. Please note that different countries report anomalies with respect to different base periods. The information provided here is based directly upon these data:

• Argentina had its highest September temperature at 1.8°C (3.2°F) above average, surpassing the previous record set in 1971 and 2012 by 0.1°C (0.2°F). The city of Buenos Aires also had its highest September temperature on record at 17.4°C (63.3°F). This value is 0.8°C (1.4°F) higher than the previous record set in 2007.
• Warmer-than-average conditions engulfed much of Spain during September 2018, resulting in Spain's warmest September on record with a national mean temperature of 23.0°C (73.4°F) or 2.4°C (4.3°F) above the 1981–2010 average. This value is 0.1°C (0.2°F) above the previous record set in 1987. Spain's national records extend back to 1965.
• The United Kingdom had cooler-than-average conditions during the month, with a national temperature of 12.4°C (54.3°F) or 0.2°C (0.4°F) below average.
• France's September 2018 national temperature was 19.0°C (66.2°F), which is 1.7°C (3.1°F) above the 1981–2010 average. September 2018 marks the sixth consecutive month in which France's national temperature has been above 1.0°C (1.8°F).
• The Kingdom of Bahrain had its second warmest mean September temperature (tied with 1998 and 2015) since national records began in 1902 at 2.1°C (3.8°F) above average. September 2017 is Bahrain's record warm September at 2.2°C (4.0°F). The nation's maximum and minimum temperatures were also the second highest on record at 2.4°C (4.3°F) and 2.8°C (5.0°F) above average, respectively.

ENSO-neutral conditions continued across the tropical Pacific Ocean during September 2018. According to NOAA's Climate Prediction Center, El Niño is favored to develop in the next few months and continue through the Northern Hemisphere winter (Southern Hemisphere summer). This forecast focuses on the ocean surface temperatures between 5°N and 5°S latitude and 170°W to 120°W longitude, called the Niño 3.4 region.

September Global Land and Ocean plot

September Global Hemisphere plot

The most current data can be accessed via the Global Surface Temperature Anomalies page.

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Year-to-date (January–September)

January–September 2018 Blended Land and Sea Surface
Temperature Anomalies in degrees Celsius

January–September 2018 Blended Land and Sea Surface
Temperature Percentiles

Warmer to much-warmer-than-average conditions engulfed much of the globe's surface during the first nine months of the year. Averaged as a whole, the January–September 2018 global land and ocean surface temperature was the fourth highest on record at 0.77°C (1.39°F) above average. This value is 0.24°C (0.43°F) less than the record high set in 2016 (+1.01°C / +1.82°F). Based on three simple scenarios, 2018 will likely end up among the five warmest years on record. Record warm temperatures were present across parts the Atlantic and Pacific Oceans, Gulf of Mexico, as well as across parts of North America, Africa, Europe, Asia, Australia, and New Zealand. No land or ocean areas had record cold January–September temperatures. However, near to much-cooler-than-average conditions were limited to Canada, the north-central contiguous U.S., parts of central Eurasia, much of the central and eastern tropical Pacific Ocean, and the northern Atlantic Ocean (off the southern coast of Greenland) and eastern Atlantic.

According to NCEI's Regional Analysis, five of six continents had a January–September temperature that ranked among the eight highest such period on record. Of note, Europe had its highest January–September on record at +1.86°C (+3.35°F), surpassing the previous record set in 2014 by +0.13°C (+0.23°F). Africa had its fifth highest year-to-date temperature, Asia and Oceania had their sixth highest on record and South America had its eighth highest. North America had its lowest year-to-date temperature departure from average since 2013.

Averaged as a whole, the global land surface temperature during January–September 2018 was 1.14°C (2.05°F) above average and the global oceans year-to-date temperature tied with 2014 as the fourth highest on record at +0.63°C (+1.13°F).

France had its highest January–September temperature since national records began in 1900 at 15.1°C (59.2°F), which is 1.4°C (2.5°F) above average. The previous record of 15.0°C (59.0°F) was set in 2003.

January–September Global Land and Ocean plot

January–September Global Hemisphere plot

The most current data can be accessed via the Global Surface Temperature Anomalies page.

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Precipitation

September

The maps below represent precipitation percent of normal (left, using a base period of 1961–90) and precipitation percentiles (right, using the period of record) based on the GHCN dataset of land surface stations. As is typical, precipitation anomalies varied significantly around the world. Precipitation during September 2018 was generally drier than normal across the western half of the contiguous U.S., Canada, northeastern Brazil, much of western and central Europe, central Russia, parts of India, and Australia. Wetter-than-normal conditions were notable across the eastern half of the contiguous U.S, northern Mexico, parts of southern South America, northern Europe, western Africa, central Asia, and Japan.

September 2018 Land-Only Precipitation
Percent of Normal

September 2018 Land-Only Precipitation Percentiles

Select national information is highlighted below. (Please note that different countries report anomalies with respect to different base periods. The information provided here is based directly upon these data):

• Exceptionally dry conditions plagued much of Australia during September 2018, giving way to the driest September since national records began in 1900 at 69% below average precipitation. Regionally, Victoria, South Australia, and Western Australia had September precipitation totals that ranked among the four lowest on record.
• September 2018 was drier than average across much of France. Averaged as a whole, France had 30% of its normal September precipitation, resulting in the third driest September since national precipitation records began in 1959, behind 1977 and 1985.

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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.

Global OHC for July–September 2018 was the highest July–September OHC in our records, which extend back to 1955. In fact, OHC for July-September 2018 is the third highest quarterly OHC in our records, with the two quarters with higher OHC than in July-September 2018 also occurring in the last 12 months. Overall, the latest quarterly OHC reveals widespread warmer than normal, i.e. the 1955-2006 mean, conditions, a situation observed since the end of 2016. As in the previous quarter, warmer than normal conditions, about 10x10^5 J/m^3, notably occupy the entire equatorial Pacific Ocean. Similarly, much higher, > 30x10^5 J/m^3, than normal OHC conditions are observed at high northern latitudes in Baffin Bay, the Greenland Sea, and the Barents Sea, and in the Gulf Stream/North Atlantic Current, the Brazil Current, and in the Kuroshio Current/Kuroshio Extension. In contrast, much cooler, < -20x10^5 J/m^3, than normal conditions continue to exist in the Subtropical western and central North Pacific Ocean. Much cooler than normal conditions persist in the subpolar North Atlantic Ocean south of Greenland and Iceland, and they extend eastward in the southern Norwegian Sea and the North Sea.

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References

• Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.
• Huang, B., V.F. Banzon, E. Freeman, J. Lawrimore, W. Liu, T.C. Peterson, T.M. Smith, P.W. Thorne, S.D. Woodruff, and H-M. Zhang, 2016: Extended Reconstructed Sea Surface Temperature Version 4 (ERSST.v4). Part I: Upgrades and Intercomparisons. J. Climate, 28, 911-930.

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Citing This Report

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