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. (2017). 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.

Supplemental December 2017 Information


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 December 2017 height and anomaly mapDecember 2017 and October - December 2017 height and anomaly mapOctober–December 2017 maps—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.


During December 2017, the most notable temperature departures from average occurred across the Northern Hemisphere land. Western Canada, Alaska, eastern Europe, and western Russia had temperature departures from average that were +4.0°C (+7.2°F) or greater. Meanwhile, western Canada, the northeastern contiguous U.S., northwestern Africa, and eastern Asia had temperatures that were -1.0°C (-1.8°F) or cooler. Across the oceans, the eastern and central tropical Pacific Ocean, the southern Atlantic Ocean, northwestern Pacific Ocean (off the coast of Japan) and parts of the Indian Ocean had near- to cooler than average conditions. Record warmth was present across Alaska, southeastern China, New Guinea and surrounding ocean, the southwestern and central Pacific Ocean, the south-central Indian Ocean, and scattered across the Atlantic Ocean. No land or ocean areas had record cold December temperatures. According to NCEI's Regional Analysis, four of six continents had a top eight warm December, with Oceania having its third warmest December on record.

The combined global average temperature over land and ocean surfaces for December 2017 was 0.80°C (1.44°F) above the 20th century average of 12.2°C (54.0°F)—tying with 2016 as the third highest December global temperature since records began in 1880. Only December 2015 and 2014 were warmer. The last five years (2013–2017) are among the ten warmest Decembers on record. December 2017 also marks the 33rd consecutive December (since 1985) and the 396th consecutive month with temperatures at least nominally above the 20th century average. The global land surface temperature for December 2017 was 1.45°C (2.61°F) above the 20th century average of 3.7°C (38.7°F) and the second highest December temperature on record, trailing behind 2015 by 0.43°C (0.77°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:

  • Cooler-than-average conditions affected parts of western Europe during December 2017. Spain's December 2017 national temperature was 0.4°C (0.7°F) below average—the 22nd coldest December since 1965. The national mean temperature across Portugal was 9.29°C (65.44°F) or 0.68°C (1.22°F) below average. The nationally-averaged minimum (nighttime) temperature was also below average at -1.82°C (-3.28°F). However, the maximum temperature for Portugal was the highest since 2000 at +0.46°C (+0.83°F).
  • December 2017 was warmer-than-average for Australia. Averaged as a whole, Australia had its highest December since 1990 and the fifth highest since national records began in 1910 at 1.10°C (1.98°F) above the 1961–1990 average. Regionally, Queensland, New South Wales, Tasmania, and the Northern Territory had a top seven warm December, with Tasmania having its second highest December temperature (+1.73°C / +3.11°F) on record, behind 2015 (+2.17°C / +3.91°F). In terms of maximum (daytime) temperatures, Australia had its sixth highest maximum temperature on record. The nationally-averaged minimum temperature tied as the fifth highest in Australia's 108-year record. Tasmania had its warmest minimum temperature for December 2017 at 1.78°C (3.20°F) above average, exceeding the previous record set in 1985 by +0.20°C (+0.36°F).
  • Warmer-than-average conditions plagued much of New Zealand during December 2017. The nationally-averaged December 2017 temperature was 18.1°C (64.6°F), which is 2.4°C (4.3°F) above the 1981–2010 average and the second highest December since national records began in 1909. According to NIWA, December 2017 also marks the third month in the 21st century to have a nationwide temperature greater than 2.0°C (3.6°F), behind February 2016 and May 2016. Several locations across New Zealand had their warmest or near-warmest December on record, including Nelson and Levin, which had their warmest December since 1862 and 1895, respectively.

The December 2017 global oceans surface temperature was 0.56°C (1.01°F) above the 20th century average of 15.7°C (60.4°F) and the sixth highest December temperature in the 138-year record.

La Niña conditions prevailed throughout December as sea surface temperatures remained below average across the eastern and central tropical Pacific Ocean. According to NOAA's Climate Prediction Center, La Niña is likely (~85–95%) through the Northern Hemisphere winter (Southern Hemisphere summer), with a transition to ENSO-neutral expected during the Northern Hemisphere spring (Southern Hemisphere fall). 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.

December Ranks and Records
(out of 138 years)
Land+1.45 ± 0.11+2.61 ± 0.20Warmest2nd2015+1.88+3.38
Ocean+0.56 ± 0.15+1.01 ± 0.27Warmest6th2015+0.84+1.51
Land and Ocean+0.80 ± 0.14+1.44 ± 0.25Warmest4th2015+1.13+2.03
Coolest135th1910, 1916-0.57-1.03
Northern Hemisphere
Land+1.64 ± 0.11+2.95 ± 0.20Warmest5th2015+2.07+3.73
Ocean+0.71 ± 0.15+1.28 ± 0.27Warmest3rd2015+0.98+1.76
Coolest136th1892, 1910-0.46-0.83
Land and Ocean+1.06 ± 0.13+1.91 ± 0.23Warmest2nd2015+1.39+2.50
Southern Hemisphere
Land+0.95 ± 0.12+1.71 ± 0.22Warmest5th2015+1.38+2.48
Ocean+0.45 ± 0.15+0.81 ± 0.27Warmest14th2015+0.75+1.35
Ties: 2005
Land and Ocean+0.53 ± 0.14+0.95 ± 0.25Warmest8th2015+0.85+1.53
Ties: 2004
Land and Ocean+2.98 ± 0.60+5.36 ± 1.08Warmest1st2017+2.98+5.36

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

Year-to-date (January–December)

Please refer to the NCEI State of the Climate Annual Global Analysis report for additional information.

January–December Ranks and Records
(out of 138 years)
Land+1.31 ± 0.15+2.36 ± 0.27Warmest3rd2016+1.44+2.59
Ocean+0.67 ± 0.16+1.21 ± 0.29Warmest3rd2016+0.76+1.37
Land and Ocean+0.84 ± 0.15+1.51 ± 0.27Warmest3rd2016+0.94+1.69
Northern Hemisphere
Land+1.42 ± 0.17+2.56 ± 0.31Warmest3rd2016+1.58+2.84
Ocean+0.79 ± 0.16+1.42 ± 0.29Warmest3rd2015+0.89+1.60
Coolest136th1908, 1909-0.47-0.85
Land and Ocean+1.03 ± 0.15+1.85 ± 0.27Warmest3rd2016+1.13+2.03
Southern Hemisphere
Land+1.05 ± 0.12+1.89 ± 0.22Warmest3rd2015, 2016+1.08+1.94
Ocean+0.58 ± 0.16+1.04 ± 0.29Warmest3rd2016+0.69+1.24
Land and Ocean+0.66 ± 0.15+1.19 ± 0.27Warmest3rd2016+0.75+1.35
Land and Ocean+1.75 ± 0.11+3.15 ± 0.20Warmest2nd2016+2.03+3.65

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



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 December 2017 varied significantly around the world. Drier-than-average conditions were present across much of the contiguous U.S., northeastern Brazil, southern South America, Spain, southeastern Europe, northeastern Australia and scattered across Asia. Wetter-than-average conditions were observed across the north-central and south-central contiguous U.S., western Alaska, northern Argentina, central and northern Europe, northern Asia, and southeastern Australia.

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):

  • Drier-than-average conditions continued to plague Portugal during December 2017, receiving only 68% of December's normal precipitation total. This marks the ninth consecutive month that precipitation totals are below average. By the end of the month, 29% of the country was in moderate drought and 64% was in severe to extreme drought.
  • The nationally-averaged precipitation total for Australia was below average for December 2017 at 13% below the 1961–1990 average. Regionally, above-average precipitation was observed in New South Wales, Victoria, Tasmania, South Australia, and Western Australia. Several locations across Victoria, southern New South Wales, and northern Tasmania to record their wettest December day on record after heavy rain fell in those areas in early December. Of note, Echuca Aerodrome, Euroa, Lake Eildon, and Strathbogie (all located in northern Victoria) had their wettest day on record for any month.
  • Precipitation totals were below average across much of New Zealand during December 2017, with several locations observing record or near-record low December precipitation totals on record. The stations at the Auckland and Paraparaumu Airports had their driest December since 1959 and 1945, respectively.

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.

October–December 2017 Ocean Heat Content (1022 joules)
Basin0-700 meters | Rank (1955-2023)
Entire BasinNorthern HemisphereSouthern Hemisphere
Source: Basin time series of heat content
October–December 2017 Heat Content 0-700 m
Heat Content 0-700 m

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 October-December 2017 was the highest October-December OHC in our records, which extend back to 1955. In fact, 2017 was the warmest year on record for the World Ocean. Overall, the latest quarterly OHC reveals widespread warmer than normal conditions, a situation observed since the last quarter of 2016. As in the previous quarter, much higher, > 30x105 J/m3, than long-term mean OHC conditions are remarkable at northern high latitudes, i.e. in the Greenland Sea, Norwegian Sea, Barents Sea, and in Baffin Bay. Similarly, much higher than normal OHC is also observed in the Gulf Stream/North Atlantic Current, the Brazil Current, the Agulhas Current and its retroflection. Cooler than normal conditions, < -20x105 J/m3, persist in the subpolar North Atlantic Ocean south of Greenland and Iceland, the western North Pacific Ocean, and along the Antarctic Circumpolar Current in the Indian Ocean and Pacific Ocean sectors. The cool signal around the Equator in the central and western Pacific Ocean during July-September 2017, is now observed in the eastern Pacific Ocean, with OHC < -10x105 J/m3 extending westward from the South America coast. Along the western boundary of the Equatorial and South Indian Ocean, cooler than normal conditions, < -20x105 J/m3, have consolidated and streghtened.


Citing This Report

NOAA National Centers for Environmental Information, Monthly Global Climate Report for December 2017, published online January 2018, retrieved on July 21, 2024 from