Global Analysis - May 2015


Maps and Time Series

Temperature and Precipitation Maps

Temperature Anomalies Time Series


Note: With this report and data release, the National Centers for Environmental Information is transitioning to improved versions of its global land (GHCN-M version 3.3.0) and ocean (ERSST version 4.0.0) datasets. Please note that anomalies and ranks reflect the historical record according to these updated versions. Historical months and years may differ from what was reported in previous reports. For more, please visit the associated FAQ and supplemental information.


Contents of this Section:


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. (2015). 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 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.

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

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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 May 2015 height and anomaly mapMay 2015 and March - May 2015 height and anomaly mapMarch–May 2015 maps—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.

May

The combined average temperature over global land and ocean surfaces for May 2015 was the highest for May in the 136-year period of record, at 0.87°C (1.57°F) above the 20th century average of 14.8°C (58.6°F), surpassing the previous record set just one year ago by 0.08°C (0.14°F). This ties with February 1998 as the fourth highest monthly departure from average for any month on record. The two highest monthly departures from average occurred earlier this year in February and March, both at 0.89°C (1.60°F) above the 20th century average for their respective months.

The average global temperature across land surfaces was 1.28°C (2.30°F) above the 20th century average of 11.1°C (52.0°F), tying with 2012 as the highest May temperature on record. Most of Earth's land surfaces were warmer than average or much warmer than average, according to the Land & Ocean Temperature Percentiles map above, with record warmth across most of Alaska, parts of tropical South America, much of southern Africa and The Middle East, and parts of northwestern Siberia. Only part of the central United States, far west central Australia, and part of Far East Russia observed temperatures characterized as "cooler than average" for May.

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):

  • Prior to the onset of the seasonal Southwest Asian Monsoon, India experienced a major heatwave during late May. As reported by the Japan Meteorological Agency, from the 21st to the 31st temperatures surpassed 42°C (108°F) across much of the country and 45°C (113°F) in northern and central India. In the capital city of New Delhi, temperatures for the period were 4°C (7°F) above the May average. More than 2200 fatalities were caused by the heat. Climatologically, May is the hottest month of the year for India.
  • Alaska observed its warmest May in its 91-year period of record. The temperature was 3.1°C (5.6°F) higher than the 1981–2010 average. The warmth was spread across the state with both Barrow in the far north and Juneau in the far southeast having a record warm May.
  • May 2015 was the second warmest for Spain since national records began in 1961, at 2.4°C (4.3°F) higher than the 1981–2010 average. Only May 1964 was warmer. The heat was most notable across the southern Iberian peninsula with temperature departures surpassing +3.5°C (+6.3°F).
  • Norway was one of the cool spots during May. The nationwide average temperature was 0.7°C (1.3°F) below the 1961–1990 average, marking the coolest May since 2005. Temperatures were not uniform across the country, however; interior regions and higher altitudes saw temperatures 2–3°C (4–5°F) below average, while parts of Finnmark and Troms in the north observed temperatures up to 3°C (5°F) above average.
  • It was also cooler than average across the UK during May, with a monthly temperature 0.8°C (1.4°F) below the 1981–2010 average. The average maximum temperature was the coldest for May since 1996.
  • All of Greenland, but particularly notable in the far northeast, was colder than average for May. Danmarkshavn was 4.6°C (8.3°F) below its 1961–1990 average, the coldest May temperature since records began there in 1949.
  • Iceland was also colder than average during May, with the coldest departures from average at the higher altitudes, 3–4°C (5–7°F) below the average of the past 10 years.

For the oceans, the May global sea surface temperature was 0.72°C (1.30°F) above the 20th century average of 16.3°C (61.3°F), the highest for May on record, surpassing the previous record set last year by 0.07°C (0.13°F). Moderate El Niño conditions were present across the central and eastern equatorial Pacific Ocean during May 2015. According to NOAA's Climate Prediction Center, there is a greater than 90 percent chance that El Niño will continue through Northern Hemisphere fall 2015, and around an 85 percent chance it will last through the 2015/16 winter. 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. Notably, record warmth was observed across much of the equatorial Pacific as well as parts of the equatorial and southern Indian Ocean and the Barents Sea to the north of Scandinavia. Only part of the North Atlantic between Greenland and the United Kingdom was much cooler than average, an area that had been record cold for several months in 2015.

May Anomaly Rank
(out of 136 years)
Records
°C °F Year(s) °C °F
Global
Land +1.28 ± 0.15 +2.30 ± 0.27 Warmest 1st 2012, 2015 +1.28 +2.30
Coolest 136th 1907 -1.00 -1.80
Ties: 2012
Ocean +0.72 ± 0.03 +1.30 ± 0.05 Warmest 1st 2015 +0.72 +1.30
Coolest 136th 1911 -0.54 -0.97
Land and Ocean +0.87 ± 0.07 +1.57 ± 0.13 Warmest 1st 2015 +0.87 +1.57
Coolest 136th 1911 -0.48 -0.86
Northern Hemisphere
Land +1.36 ± 0.14 +2.45 ± 0.25 Warmest 2nd 2012 +1.51 +2.72
Coolest 135th 1907 -1.09 -1.96
Ocean +0.82 ± 0.03 +1.48 ± 0.05 Warmest 1st 2015 +0.82 +1.48
Coolest 136th 1911 -0.52 -0.94
Land and Ocean +1.03 ± 0.07 +1.85 ± 0.13 Warmest 1st 2015 +1.03 +1.85
Coolest 136th 1907 -0.61 -1.10
Southern Hemisphere
Land +1.04 ± 0.22 +1.87 ± 0.40 Warmest 3rd 2014 +1.25 +2.25
Coolest 134th 1917 -1.16 -2.09
Ocean +0.65 ± 0.04 +1.17 ± 0.07 Warmest 1st 2015 +0.65 +1.17
Coolest 136th 1911 -0.54 -0.97
Land and Ocean +0.71 ± 0.06 +1.28 ± 0.11 Warmest 1st 2014, 2015 +0.71 +1.28
Coolest 136th 1911 -0.53 -0.95
Ties: 2014

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

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Seasonal (March–May)

Together, the record warm March and May and fourth warmest April made the combined average temperature over global land and ocean surfaces for the March–May period (austral autumn / boreal spring) the highest on record, at 0.85°C (1.53°F) above the 20th century average of 13.7°C (56.7°F), surpassing the previous record warmth of March–May 2010 by 0.04°C (0.07°F). The Northern Hemisphere had its warmest spring on record and the Southern Hemisphere had its second warmest autumn, behind 2010.

The globally-averaged temperature across land surfaces was the highest on record for March–May, at 1.33°C (2.39°F) above the 20th century average of 8.1°C (46.4°F). Most of western North America, South America, Africa, and Eurasia was much warmer than average, with a few regions within these areas record warm, as shown by the Land & Ocean Temperature Percentiles map above. Only small areas of the south central United States and north central Mexico, along with northeastern Canada, western Greenland, and western Australia were cooler or much cooler than average. No land areas observed record cold during March–May.

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):

  • Norway experienced a warm spring, at 1.6°C (2.9°F) above the 1961–1990 average. The greatest departures from average were observed in the north, with Finnmark 3–4°C (5–7°F) warmer than average.
  • Spring was also warm in France, with an average temperature 0.8°C (1.4°F) higher than the 1981–2010 average.
  • Autumn was warm for New Zealand overall, with a nationally averaged temperature 0.8°C (1.4°F) above the 1981–2010 average. The warmest regions were in isolated parts of inland Taranaki, eastern Canterbury and the West Coast, where temperatures were more than 1.2°C (2.2°F) above average, according to NIWA.
  • Autumn was record warm for Argentina among the country's 55-year period of record, at 1.51°C (2.72°F) higher than the 1961–1990 average. The entire country observed March–May temperatures above average, with much of the central to northwest regions of the country 1.5–3.0°C (2.7–5.4°F) above average.

Across the world's oceans, the March–May sea surface temperature was 0.66°C (1.19°F) above the 20th century average of 16.1°C (61.0°F), also the highest for March–May on record, surpassing the previous record of 2010 by 0.02°C (0.04°F). The oceans in the Northern Hemisphere and in the Southern Hemisphere were each record warm. Record warm areas were particularly notable across much of the northeastern and equatorial Pacific Ocean, parts of the western Atlantic stretching into the Gulf of Mexico, and the Barents Sea north of Scandinavia. Much cooler than average temperatures and an area of record cold for the season was observed in the North Atlantic south of Greenland.

March–May Anomaly Rank
(out of 136 years)
Records
°C °F Year(s) °C °F
Global
Land +1.33 ± 0.17 +2.39 ± 0.31 Warmest 1st 2015 +1.33 +2.39
Coolest 136th 1898 -0.87 -1.57
Ocean +0.66 ± 0.03 +1.19 ± 0.05 Warmest 1st 2015 +0.66 +1.19
Coolest 136th 1911 -0.53 -0.95
Land and Ocean +0.85 ± 0.08 +1.53 ± 0.14 Warmest 1st 2015 +0.85 +1.53
Coolest 136th 1911 -0.53 -0.95
Northern Hemisphere
Land +1.50 ± 0.22 +2.70 ± 0.40 Warmest 1st 2015 +1.50 +2.70
Coolest 136th 1898 -0.93 -1.67
Ocean +0.73 ± 0.04 +1.31 ± 0.07 Warmest 1st 2015 +0.73 +1.31
Coolest 136th 1911 -0.49 -0.88
Land and Ocean +1.02 ± 0.12 +1.84 ± 0.22 Warmest 1st 2015 +1.02 +1.84
Coolest 136th 1909 -0.57 -1.03
Southern Hemisphere
Land +0.90 ± 0.18 +1.62 ± 0.32 Warmest 6th 2010 +1.11 +2.00
Coolest 131st 1917 -0.89 -1.60
Ties: 2009
Ocean +0.62 ± 0.03 +1.12 ± 0.05 Warmest 1st 2010, 2015 +0.62 +1.12
Coolest 136th 1911 -0.55 -0.99
Ties: 2010
Land and Ocean +0.67 ± 0.07 +1.21 ± 0.13 Warmest 2nd 2010 +0.69 +1.24
Coolest 135th 1911 -0.55 -0.99

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

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Year-to-date (January–May)

The first five months of 2015 were the warmest such period on record across the world's land and ocean surfaces, at 0.85°C (1.53°F) above the 20th century average, surpassing the previous record set in 2010 by 0.09°C (0.16°F). Consequently, 2010 was the last year with El Niño conditions; however El Niño was ending at this point in 2010, while it appears to be maturing at the same point in 2015.

The average global sea surface temperature for the year-to-date was the highest for January–May in the 136-year period of record, surpassing the previous record of 2010 by 0.01°C (0.02°F). while the average land surface temperature was also record high, surpassing the previous record of 2007 by 0.05°C (0.09°F). Record warmth was most notable over the oceans, particularly the northeastern and equatorial Pacific Ocean, parts of the western North Atlantic, and the Barents Sea north of Scandinavia.

January–May Anomaly Rank
(out of 136 years)
Records
°C °F Year(s) °C °F
Global
Land +1.42 ± 0.20 +2.56 ± 0.36 Warmest 1st 2015 +1.42 +2.56
Coolest 136th 1893 -1.00 -1.80
Ocean +0.63 ± 0.03 +1.13 ± 0.05 Warmest 1st 2015 +0.63 +1.13
Coolest 136th 1911 -0.51 -0.92
Land and Ocean +0.85 ± 0.09 +1.53 ± 0.16 Warmest 1st 2015 +0.85 +1.53
Coolest 136th 1911 -0.53 -0.95
Northern Hemisphere
Land +1.63 ± 0.25 +2.93 ± 0.45 Warmest 1st 2015 +1.63 +2.93
Coolest 136th 1893 -1.18 -2.12
Ocean +0.70 ± 0.05 +1.26 ± 0.09 Warmest 1st 2015 +0.70 +1.26
Coolest 136th 1911 -0.47 -0.85
Land and Ocean +1.05 ± 0.13 +1.89 ± 0.23 Warmest 1st 2015 +1.05 +1.89
Coolest 136th 1893 -0.69 -1.24
Southern Hemisphere
Land +0.89 ± 0.17 +1.60 ± 0.31 Warmest 6th 2010 +1.09 +1.96
Coolest 131st 1917 -0.83 -1.49
Ocean +0.59 ± 0.04 +1.06 ± 0.07 Warmest 2nd 2010 +0.62 +1.12
Coolest 135th 1911 -0.52 -0.94
Ties: 1998
Land and Ocean +0.64 ± 0.07 +1.15 ± 0.13 Warmest 3rd 2010 +0.69 +1.24
Coolest 134th 1911 -0.54 -0.97

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

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Precipitation

May

The maps 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. As is typical, precipitation anomalies during May 2015 varied significantly around the world.

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):

  • The heat in Spain during May was accompanied by extreme dryness. With precipitation records dating back to 1947, May 2015 was the driest May on record for the country, with total average rainfall for the month just 25 percent of normal.
  • On the other hand, it was wet in Denmark. The country experienced its second wettest May (tied with May 1969) since national records began in 1874, with 86 mm of precipitation. The wettest May occurred in 1983.

Seasonal (March–May)

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 March–May 2015 varied significantly around the world.

  • Spring was not only warm in Norway, but also wet. The average rainfall total for the March–May period was 140 percent of normal. Several stations in western Norway received 200–250 percent of their average seasonal precipitation.
  • Spring was also wet in Denmark, where the country had its wettest spring since 1983, with 179 mm of total precipitation during March–May. This also marked the ninth wettest spring in the 142-year period of record..

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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, 2015: 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

NOAA National Centers for Environmental Information, State of the Climate: Global Analysis for May 2015, published online June 2015, retrieved on July 4, 2015 from http://www.ncdc.noaa.gov/sotc/global/201505.