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.
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 October 2017 map—is generally reflected by areas of positive and negative temperature anomalies at the surface, respectively.
October 2017 was characterized by warmer-than-average conditions across much of the world's land and ocean surfaces, with record warmth scattered across the globe. The largest positive anomalies were observed across north-central Russia, Alaska, northwestern and eastern Canada, and the northeastern contiguous U.S., where temperature departures from average were +3.0°C (+5.4°F) or higher. Near to cooler-than-average conditions were present across much of central Asia (stretching from western Russia to Kazakhstan, Mongolia, and eastern China), the western contiguous U.S., northern and southern Africa, as well the eastern tropical and southeastern Pacific Ocean, northwestern Pacific Ocean (off the coast of Russia and Japan), eastern Indian Ocean, and scattered across the Atlantic Ocean. No land or ocean areas had record cold October temperatures.
The combined average temperature over global land and ocean surfaces for October 2017 was 0.73°C (1.31°F) above the 20th century average of 14.0°C (57.1°F). This value tied with 2003 as the fourth highest October temperature on record since global records began in 1880, behind 2015 (+1.0°C / +1.8°F), 2014 (+0.79°C / +1.42°F), and 2016 (+0.74°C / +1.33°F). The 10 warmest Octobers on record have all occurred during the 21st century, specifically since 2003. October 2017 also marks the 41st consecutive October and the 394th consecutive month with temperatures at least nominally above the 20th century average. The global land surface temperature was the 11th highest for October at 0.99°C (1.78°F) above the 20th century average of 9.3°C (48.7°F). According to NCEI's Regional Analysis, Oceania had its sixth highest October temperature on record, with North America, South America, and Europe having its 10th or 11th warmest October on record. Meanwhile, Africa had its coldest October since 2011. The October 2017 global ocean temperature was 0.63°C (1.13°F) above the 20th century average of 15.9°C (60.6°F), the fourth highest October temperature in the 138-year record.
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:
- Portugal's October 2017 mean temperature was the highest for the month of October since national records began in 1931 at +3.0°C (5.4°F) above average. Portugal's daytime (maximum) and minimum (nighttime) temperatures were also warmer than average at 5.0°C (9.0°F) and 1.0°C (1.8°F) above average, respectively. The national maximum temperature for October 2017 was also the highest since 1931. During the month of October, the nation experienced two heat waves (October 1–16 and October 23–30). The first heat wave lasted for 16 days and ranked among the longest for the month of October.
- Much-warmer-than-average conditions engulfed much of Spain during October 2017, resulting in the nation's second highest October temperature since national records began in 1965. Spain's October 2017 mean temperature was 18.5°C (65.3°F), which is 2.6°C (4.7°F) above the 1981–2010 average and falls behind the record year set in 2014 by 0.2°C (0.4°F).
- The Kingdom of Bahrain had its second highest October temperature since national records began in 1902 at 31.1°C (88.0°F) or 1.9°C (3.4°F) above average. This value falls behind October 2015 when the national mean temperature was 31.7°C (89.1°F). The national maximum and minimum temperatures were also above average at 1.9°C (3.4°F) and 2.1°C (3.8°F), respectively. This was the seventh highest maximum temperature for October and the fourth highest minimum temperature.
- The national average temperature for Australia for October 2017 was 1.42°C (2.56°F) above the 1961–1990 average and the tenth highest October temperature in the nation's 108-year record. Regionally, Queensland, New South Wales, Victoria, and Tasmania had a top nine warm October. New South Wales had the largest positive temperature departure from average at +2.16°C (+3.89°F) and the fourth highest for New South Wales on record. The nation's maximum and minimum temperatures were also above average. However, the high mean temperature value across the nation was mainly driven by very warm minimum (nighttime) temperatures, which were 1.51°C (2.72°F) above average and the third highest for Australia on record. Queensland, New South Wales, and Tasmania had a top four warm minimum temperature since records began in 1910.
Weak La Niña conditions developed across the tropical Pacific Ocean during October 2017. According to NOAA's Climate Prediction Center, La Niña conditions are expected to continue (65–75% chance) through the Northern Hemisphere winter (Southern Hemisphere summer) 2017–18. 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.
(out of 138 years)
|Land||+0.99 ± 0.20||+1.78 ± 0.36||Warmest||11th||2015||+1.37||+2.47|
|Ocean||+0.63 ± 0.15||+1.13 ± 0.27||Warmest||4th||2015||+0.86||+1.55|
|Land and Ocean||+0.73 ± 0.14||+1.31 ± 0.25||Warmest||4th||2015||+1.00||+1.80|
|Land||+0.95 ± 0.22||+1.71 ± 0.40||Warmest||10th||2011||+1.34||+2.41|
|Ocean||+0.80 ± 0.14||+1.44 ± 0.25||Warmest||4th||2015||+1.05||+1.89|
|Land and Ocean||+0.86 ± 0.18||+1.55 ± 0.32||Warmest||3rd||2015||+1.14||+2.05|
|Land||+1.10 ± 0.17||+1.98 ± 0.31||Warmest||7th||2015||+1.62||+2.92|
|Ocean||+0.51 ± 0.15||+0.92 ± 0.27||Warmest||8th||2015||+0.73||+1.31|
|Land and Ocean||+0.60 ± 0.14||+1.08 ± 0.25||Warmest||8th||2015||+0.87||+1.57|
|Land and Ocean||+1.33 ± 0.41||+2.39 ± 0.74||Warmest||9th||1947, 2011||+1.78||+3.20|
The most current data can be accessed via the Global Surface Temperature Anomalies page.
The first ten months of the year were characterized by much-warmer-than-average conditions across much of the world's land and ocean surface. Record warmth was observed across eastern Asia, western and central parts of the Pacific Ocean, southwestern Europe, western and northern Indian Ocean, and scattered across Africa, Australia, southern North and South America. Near to cooler-than-average conditions were present across the northern Pacific Ocean, northern Atlantic Ocean, and eastern Indian Ocean. No land or ocean areas had record cold temperatures for the year-to-date. According to NCEI's Global Regional Analysis, all six continents had a top six warm January–October period since continental records began in 1910, with South America having its second highest such period on record, behind 2015. Averaged as a whole, the January–October 2017 global land and ocean surface temperature was the third highest for January–October since global records began in 1880 at 0.86°C (1.55°F) above the 20th century average of 14.1°C (57.4°F), behind 2016 (highest) and 2015 (second highest). Nine of the 10 warmest January-October global land and ocean temperatures occurred during the 21st century (since 2005), with only one year from the 20th century (1998) among the top 10. With two months remaining, the 2017 global land and ocean temperature will likely end among the three highest in the 138-year record.
The global land surface temperature was 1.33°C (2.39°F) above the 20th century average of 9.3°C (48.7°F) and the second highest January–October temperature since global records began in 1880, behind 2016. The global ocean surface temperature was the third highest such period at 0.68°C (1.22°F) above the 20th century average of 16.1°C (61.0°F), behind 2016 and 2015.
(out of 138 years)
|Land||+1.33 ± 0.17||+2.39 ± 0.31||Warmest||2nd||2016||+1.51||+2.72|
|Ocean||+0.68 ± 0.18||+1.22 ± 0.32||Warmest||3rd||2016||+0.78||+1.40|
|Land and Ocean||+0.86 ± 0.17||+1.55 ± 0.31||Warmest||3rd||2016||+0.98||+1.76|
|Land||+1.42 ± 0.20||+2.56 ± 0.36||Warmest||2nd||2016||+1.67||+3.01|
|Ocean||+0.79 ± 0.17||+1.42 ± 0.31||Warmest||3rd||2016||+0.88||+1.58|
|Land and Ocean||+1.03 ± 0.17||+1.85 ± 0.31||Warmest||3rd||2016||+1.18||+2.12|
|Land||+1.10 ± 0.14||+1.98 ± 0.25||Warmest||2nd||2016||+1.11||+2.00|
|Ocean||+0.60 ± 0.18||+1.08 ± 0.32||Warmest||3rd||2016||+0.71||+1.28|
|Land and Ocean||+0.68 ± 0.17||+1.22 ± 0.31||Warmest||3rd||2016||+0.77||+1.39|
|Land and Ocean||+1.65 ± 0.14||+2.97 ± 0.25||Warmest||2nd||2016||+2.19||+3.94|
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 vary significantly around the world. October precipitation was generally drier than normal across parts of the western half of the contiguous U.S., northern Mexico, western Europe, central and interior southern Asia, western Australia, and much of South America. Wetter-than-normal conditions were notable across the eastern half of the contiguous U.S., eastern Europe, eastern Africa, southern India, northeastern Australia, Japan, and across parts of southern South America.
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 October 2017, receiving only 30% of its October normal precipitation total. This was the driest October in the last 20 years. The warmer-than-average conditions and lack of precipitation contributed to high evapotranspiration values and significant soil moisture deficit. About 75.2% of the nation was experiencing extreme drought conditions by the end of the month, according to the Palmer Drought Severity Index (PDSI).
- The nationally-average precipitation total across France ranked as the fifth driest since national records began in 1959 at nearly 30% of its normal precipitation for the month of October.
- Wetter-than-average conditions were present across much of Australia during October 2017, resulting in 155% of average normal precipitation for the month. Many of the regions had above-average conditions, with Queensland receiving 273% of normal October precipitation. This was Queensland's third wettest October since records began in 1900.
- Southern and western Finland had wetter-than-average conditions for the month, while northern parts of the country were drier-than-average. Of note, Nuuksio (a district of Espoo) had a total of 226.1 mm (8.9 inches) for October 2017, which is only 2 mm (0.08 inch) shy of tying the nation's record for the month, which was set in Hiiskula, Vihti in 2006.
- 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.