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Note: GHCN-M Data Notice

An omission in processing a correction algorithm led to some small errors on the Global Historical Climatology Network-Monthly dataset (GHCN-M v3.2.0). This led to small errors in the reported land surface temperatures in the October, November, December and Annual U.S. and global climate reports. On February 14, 2013, NCDC fixed this error in its software, included an additional improvement (described below), and implemented both changes as GHCN-M version 3.2.1. With this update to GHCN-M, the Merged Land and Ocean Surface Temperature dataset also is subsequently revised as MLOST version 3.5.3.

The net result of this new version of GHCN-M reveals very small changes in temperature and ranks. The 2012 U.S. temperature is 0.01°F higher than reported in early January, but still remains approximately 1.0°F warmer than the next warmest year, and approximately 3.25°F warmer than the 20th century average. The U.S. annual time series from version 3.2.1 is almost identical to the series from version 3.2.0 and that the 1895-2012 annual temperature trend remains 0.13°F/decade. The trend for certain calendar months changed more than others (discussed below). For the globe, ranks of individual years changed in some instances by a few positions, but global land temperature trends changed no more than 0.01°C/century for any month since 1880.

NCDC uses two correction processes to remove inhomogeneities associated with factors unrelated to climate such as changes in observer practices, instrumentation, and changes in station location and environment that have occurred through time. The first correction for time of observation changes in the United States was inadvertently disabled during late 2012. That algorithm provides for a physically based correction for observing time changes based on station history information. NCDC also routinely runs a .pairwise correction. algorithm that addresses such issues, but in an indirect manner. It successfully corrected for many of the time of observation issues, which minimized the effect of this processing omission.

The version 3.2.1 release also includes the use of updated data to improve quality control and correction processes of other U.S. stations and neighboring stations in Canada and Mexico.

Compared to analyses released in January 2013, the trend for certain calendar months has changed more than others. This effect is related to the seasonal nature of the reintroduced time-of-observation correction. Trends in U.S. winter temperature are higher while trends in summer temperatures are lower. For the globe, ranks of individual years changed in some instances by a few positions, but global temperature trends changed no more than 0.01°C/century for any month since 1880.

More complete information about this issue is available at this supplemental page.

NCDC will not update the static reports from October through December 2012 and the 2012 U.S and Global annual reports, but will use the current dataset (GHCN-M v. 3.2.1 and MLOST v. 3.5.3) for the January 2013 report and other comparisons to previous months and years.

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Global Highlights

  • The combined average temperature over global land and ocean surfaces for May 2013 tied with 1998 and 2005 as the third warmest on record, at 0.66°C (1.19°F) above the 20th century average of 14.8°C (58.6°F).
  • The global land surface temperature was 1.11°C (2.00°F) above the 20th century average of 11.1°C (52.0°F), also the third warmest May on record. For the ocean, the May global sea surface temperature was 0.49°C (0.88°F) above the 20th century average of 16.3°C (61.3°F), tying with 2003 and 2009 as the fifth warmest May on record.
  • The combined global land and ocean average surface temperature for the March–May period was 0.59°C (1.06°F) above the 20th century average of 13.7°C (56.7°F), tying with 2004 as the eighth warmest such period on record.
  • The March–May worldwide land surface temperature was 0.97°C (1.75°F) above the 20th century average, the 11th warmest such period on record. The global ocean surface temperature for the same period was 0.45°C (0.81°F) above the 20th century average and tied with 2001 as the seventh warmest such period on record.
  • The combined global land and ocean average surface temperature for the January–May period (year-to-date) was 0.59°C (1.06°F) above the 20th century average of 13.1°C (55.5°F), the eighth warmest such period on record.


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.v3b) anomaly analysis developed by Smith et al. (2008). Temperature anomalies for land and ocean are analyzed separately and then merged to form the global analysis. For more information, please visit NCDC's Global Surface Temperature Anomalies page. The May 2013 Global State of the Climate report introduces percentile maps that complement the information provided by the anomaly maps. These new maps on the right provide 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.


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 May 2013 height and anomaly mapMay 2013 and March - May 2013 height and anomaly mapMarch–May 2013 maps—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.


May 2013 tied with 1998 and 2005 as the third warmest May in the 134-year period of record across global land and ocean surfaces, at 0.66°C (1.19°F) above the 20th century average. As indicated by the global temperature percentile maps above, several regions around the world had record warmth, including north central Siberia, west central Australia, parts of northern and eastern Europe, parts of Libya and Algeria in northern Africa, part of northeastern China, the Philippines, and part of northern South America. Record cold was observed in western Greenland. Overall, the average global temperature across land surfaces was 1.11°C (2.00°F) above the 20th century average, marking the third warmest May on record. The average land temperature in the Northern Hemisphere was fifth warmest on record, while the Southern Hemisphere—which has considerably less land surface area than the Northern Hemisphere—was second warmest on record.

Select national information is highlighted below:
  • According to the Finnish Meteorological Institute, May was unusually warm across the country, with the greatest warmth in the north. Temperatures were 4°C (7°F) above average in northernmost Lapland and 2°–3°C (4°–6°F) above average in southern and western Finland.

  • Norway observed one of its warmest Mays in the country's 113-year period of record, with a monthly average temperature 2.6°C (4.7°F) above the 1971–2000 average. Trøndelag region was record warm and Northern Norway was second warmest on record.

  • Iceland observed a monthly average temperature that was 0.5°C (0.9°F) below the 1961–1990 average, marking the coolest May since 2005.

  • May 2013 ranked among the top five warmest Mays over the past century for Sweden. Several stations were record warm, including Sarna in northern Dalarna (records began in 1892) and Östersund / Frösön (records began in 1937) that were 10.4°C (18.7°F) and 10.5°C (18.9°F) above their respective averages. Many other stations reported near-record warmth for the month.

  • The nationally-averaged monthly May temperature for Spain was 1.3°C (2.3°F) below the long-term mean, the coldest May on record since 1985 according to AEMet. The coldest anomalies were observed across the north of the country. The port city of Santander, Catabria on the north coast had its coolest May since records began in 1951.

  • The Republic of Moldova had monthly temperatures that were 2.5–3.5°C (4.5–6.3°F) above normal, an event that occurs on average every 10 to 15 years, according to Moldova's national meteorological agency, Serviciul Hidrometeorologic de Stat.

  • The nationally-averaged May maximum temperature for Australia was 0.80°C (1.44°F) above the 1961–1990 average. Anomalies were highest over South Australia, with a monthly temperature of 2.38°C (4.28°F) above average, the fourth warmest May in its 104-year period of record. The May minimum temperature was record high for the state, at 2.57°C (4.63°F) above average, breaking the previous record set in 1921 by 0.32°C (0.58°F). Western Australia and the Northern Territory each had top 10 warm minimum May temperatures.

  • At the South Pole station in Antarctica, the average May temperature was -62.4°C (-80.3°F), 4.5°C (-8.1°F) below average. Minimum temperature records were broken at this station on two days during the month.

The average global sea surface temperature for May was 0.49°C (0.88°F) above average, tying with 2003 and 2009 as the fifth warmest May on record. Prior to the start of the Atlantic hurricane season, which begins June 1st, sea surface temperatures in the Main Development Region of this basin were much warmer than average. Generally, higher-than-average temperatures in this region are one of the factors that help provide ideal conditions for an active hurricane season. For the 14th straight month, ENSO conditions across the eastern and central equatorial Pacific Ocean remained neutral; however, below-average sea surface temperatures in the eastern equatorial Pacific did strengthen compared with the previous month. According to NOAA's Climate Prediction Center, neutral conditions are favored through the Northern Hemisphere summer 2013. Elsewhere, record warm sea surface temperatures were observed in part of the northeastern Pacific, the western equatorial Pacific near the Philippines, sections of the Indian Ocean off of the southern Australian coast, and the eastern Mediterranean Sea. No record cold ocean surface temperatures were observed across the globe during May. Images of sea surface temperature conditions are available for all weeks during 2013 from the weekly SST page

May Ranks and Records
(out of 134 years)
Land+1.11 ± 0.14+2.00 ± 0.25Warmest3rd2012+1.25+2.25
Ocean+0.49 ± 0.04+0.88 ± 0.07Warmest5th1998+0.57+1.03
Ties: 2003, 2009
Land and Ocean+0.66 ± 0.07+1.19 ± 0.13Warmest3rd2010+0.72+1.30
Ties: 1998, 2005
Northern Hemisphere
Land+1.14 ± 0.15+2.05 ± 0.27Warmest5th2012+1.48+2.66
Ocean+0.49 ± 0.04+0.88 ± 0.07Warmest4th2005+0.59+1.06
Land and Ocean+0.74 ± 0.08+1.33 ± 0.14Warmest3rd2012+0.85+1.53
Southern Hemisphere
Land+1.03 ± 0.23+1.85 ± 0.41Warmest2nd2002+1.04+1.87
Ocean+0.50 ± 0.04+0.90 ± 0.07Warmest8th1998+0.62+1.12
Land and Ocean+0.58 ± 0.06+1.04 ± 0.11Warmest4th1998+0.68+1.22
Ties: 2009
Land and Ocean+1.31 ± 0.27+2.36 ± 0.49Warmest7th2010+1.92+3.46
Seasonal (March–May)

The average global March–May temperature was 0.59°C (1.06°F) above the 20th century average, tying with 2004 as the eighth warmest such period on record. Boreal spring in the Northern Hemisphere was 10th warmest on record and austral fall in the Southern Hemisphere was seventh warmest. The average temperature over land surfaces around the world during March–May was 0.97°C (1.75°F) higher than the long-term average and the 11th warmest March–May on record, while the average temperature over global ocean surfaces was 0.45°C (0.81°F) above average, tying with 2001 as the seventh warmest on record for the period. As indicated by the global tempertaure percentile maps above, record warmth was observed in southeastern Mali, western Libya, parts of the eastern Mediterranean Sea and eastern Europe, central northern China, much of the Philippines, sections of central and southern Australia, and part of the Indian Ocean south of Australia. No regions of the globe had record cold March–May temperatures, although parts of the central and southern continental United States, southeastern Alaska, and England were much cooler than average. While ENSO-neutral conditions were reflected by the near-average temperatures in the central and eastern equatorial Pacific Ocean, most other equatorial oceanic regions around the globe were much warmer than average.

Select national information is highlighted below:
  • With a cooler-than-average March and May and near-average April, the average spring temperature in France was 1.3°C (2.3°F) below normal, making this the country's coolest spring since 1987. Northern France saw temperatures 1°–2°C (2°–4°F) below average, while the south had temperatures up to 1°C (2°F) below average.

  • Combining an unusually cold March with an above-average May, the nationally-averaged spring temperature across Finland was below average for the period.

  • The Netherlands reported its coldest spring in more than 40 years. Due in large part to a colder-than-average March, the average spring temperature in De Bilt was 2.1°C (3.8°F) below the 1981–2010 average. There were 28 frost days (minimum temperature below 0°C / 32°F) compared with the average of 9.

  • With records dating back to 1909, the nationally-averaged fall (March–May) temperature across New Zealand was 0.7°C (1.3°F) above the 1971–2010 average. The highest anomalies were observed in the Bay of Plenty and parts of the Waikato region, with temperatures more than 1.2°C (2.2°F) above average.
  • Fall (March–May) 2013 in Australia tied for the eighth warmest maximum temperature in the country's 104-year period of record, at 1.03°C (1.85°F) above the 1961–1990 average. The states of Victoria, Tasmania, and South Australia all experienced top five maximum temperatures for the season, while the Northern Territory was ninth warmest. Every state and territory had above-average maximum and minimum temperatures for the period.

March–May Ranks and Records
(out of 134 years)
Land+0.97 ± 0.13+1.75 ± 0.23Warmest11th2010+1.30+2.34
Ocean+0.45 ± 0.05+0.81 ± 0.09Warmest7th1998+0.57+1.03
Ties: 2001
Land and Ocean+0.59 ± 0.08+1.06 ± 0.14Warmest8th2010+0.76+1.37
Ties: 2004
Northern Hemisphere
Land+1.01 ± 0.16+1.82 ± 0.29Warmest10th2012+1.41+2.54
Ocean+0.45 ± 0.05+0.81 ± 0.09Warmest6th2010+0.56+1.01
Land and Ocean+0.66 ± 0.10+1.19 ± 0.18Warmest10th2010+0.87+1.57
Ties: 2004, 2011
Southern Hemisphere
Land+0.86 ± 0.18+1.55 ± 0.32Warmest7th2010+1.11+2.00
Ocean+0.46 ± 0.05+0.83 ± 0.09Warmest10th1998+0.62+1.12
Land and Ocean+0.52 ± 0.07+0.94 ± 0.13Warmest7th1998+0.67+1.21
Land and Ocean+0.68 ± 0.10+1.22 ± 0.18Warmest27th1990+2.34+4.21

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

Year-to-date (January–May)

The globally-averaged temperature across land and ocean surfaces for the first five months of 2013 (January–May) was 0.59°C (1.06°F) higher than the 20th century average, ranking as the eighth warmest such period on record. The average global land temperature was the sixth warmest for the period, while the average global ocean surface temperature was eighth warmest. While ranking among the top 10, the global land, global ocean, and combined global land and ocean were all still cooler compared with 2012, a period when ENSO-neutral conditions were also present. The record warmest January–May occurred in 2010, where a warm El Niño phase was present during January–April before transitioning to ENSO-neutral conditions by May.

January–May Ranks and Records
(out of 134 years)
Land+1.00 ± 0.20+1.80 ± 0.36Warmest6th2007+1.35+2.43
Ocean+0.43 ± 0.05+0.77 ± 0.09Warmest8th1998, 2010+0.56+1.01
Land and Ocean+0.59 ± 0.10+1.06 ± 0.18Warmest8th2010+0.72+1.30
Northern Hemisphere
Land+1.03 ± 0.23+1.85 ± 0.41Warmest9th2007+1.52+2.74
Ocean+0.43 ± 0.06+0.77 ± 0.11Warmest6th2010+0.55+0.99
Coolest129th1910, 1911-0.47-0.85
Ties: 2002
Land and Ocean+0.66 ± 0.13+1.19 ± 0.23Warmest7th2007+0.86+1.55
Southern Hemisphere
Land+0.92 ± 0.16+1.66 ± 0.29Warmest4th2010+1.11+2.00
Ocean+0.45 ± 0.05+0.81 ± 0.09Warmest10th1998+0.61+1.10
Ties: 2007
Land and Ocean+0.52 ± 0.07+0.94 ± 0.13Warmest6th1998, 2010+0.66+1.19
Ties: 2004, 2007
Land and Ocean+0.56 ± 0.19+1.01 ± 0.34Warmest30th1995+1.76+3.17
Ties: 1992, 2001

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


The maps below represent precipitation percent of normal (left) and precipitation percentiles (right) based on the GHCN dataset of land surface stations using a base period of 1961–1990. As is typical, precipitation anomalies during May 2013 varied significantly around the world. As indicated by the May precipitation percentiles map below, record wetness was observed over parts of the north central United States, far southwestern Canada, part of central Europe, and a section of Far East Russia. Record dryness was scattered across different parts of the globe, including part of northern Chile, northern South Africa, eastern Niger, south central Ukraine, and parts of southern Kazakhstan.

  • Monthly precipitation in Norway was 150 percent of average, ranking this month among the 10 wettest Mays on record. Far northern Norway reported precipitation that was five times higher than average for the month. The Eastern Region was record wet for May.

  • Austria tied with 1962 and 1965 as the wettest May in the country's 156-year period of record. Rainfall was almost two times the 1981–2010 average.

  • The average May 2013 rainfall in Germany was 128.2 mm (179.0 percent of normal), the second highest for May, behind 2007, in the country's 133-year period of record.

  • With low pressure systems abundant over eastern New Zealand, the capital city of Auckland observed its wettest May on record, at 250 percent of normal rainfall, according to NIWA. More than 150 percent of normal May rainfall was recorded in large parts of Waikato, Canterbury, Otago, and New Plymouth.

  • Nationally-averaged May precipitation across Australia was the highest since 1997, at 125 percent of the 1961–1990 average. However, rainfall was not evenly distributed as the northwestern to central parts of the country received the most anomalous rainfall, while the eastern regions and part of the north received the least.

  • Precipitation during March–May was below average for almost all of Finland. The driest anomalies were measured in Southeastern Finland and in southern and northwestern Lapland, where precipitation was less than 60 percent of average.

  • France had one of its wettest springs on record since 1959, with 130 percent of typical March–May precipitation averaged across the country, according to Meteo France. The highest precipitation anomalies were observed in the Southeast, Corsica, and southern Burgundy Champagne-Ardenne and the southern Aquitaine.


Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R.G., T.C. Peterson, A.N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T.M. and R.W. Reynolds, 2005: A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

Smith et al., 2008, Improvements to NOAA's Historical Merged Land-Ocean Surface Temperature Analysis (1880-2006), J. Climate., 21, 2283-2293.

Citing This Report

NOAA National Centers for Environmental Information, Monthly Global Climate Report for May 2013, published online June 2013, retrieved on April 14, 2024 from