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Climate bulletin - October 2014

Temperature anomalies relative to the 1961 - 1990 average.

Summary of the world's climate in October 2014.

The global average temperature for October 2014 as estimated from the HadCRUT4 data set was 0.61 ± 0.14 °C above the 1961-1990 average. Although the central estimate of 0.61 °C for October 2014 suggests that it was the warmest October on record, the difficulties of measuring global average temperature are such that it is not possible to provide a definitive ranking. Other very warm Octobers were comparable within the estimated margin of error. Other global temperature data sets maintained by NASA GISS and NOAA NCDC also show that October was a very warm month globally. Sea-surface temperatures in the tropical Pacific were close to or above average in October, but did not exceed El Niño thresholds.

During October, the global average air temperature over land was warmer than the long term average (0.95 ± 0.26 °C). Cooler than average land surface temperatures were recorded across large areas of central Eurasia and more limited areas of eastern Eurasia. In European Russia, in the second half of the month, a number of stations broke daily low minimum temperature records for the month. Except for northern Australia, New Zealand and limited areas of the Americas, most other land areas were warmer than average, with significant warmth - exceeding the 90th percentile of occurrence - extending across western Europe into north Africa, southern Australia, the far northeast and southern parts of Eurasia, the western US and Canada, eastern Canada, and an area of South America including northern Argentina, Paraguay, Bolivia and Southern Brazil. A heat wave in October affected northern Argentina, southern Brazil, Bolivia and Paraguay with a number of stations reporting daily temperature records for the time of year.

Sea-surface temperatures were generally warmer than average in October. The global mean sea-surface temperature was 0.53 ± 0.08 °C above the long term average. The northern hemisphere was particularly warm (as it had been during the northern-hemisphere summer months), with the northern hemisphere average being 0.74 ± 0.08 °C above the 1961-1990 average. Unusually high sea-surface temperatures were widespread in the northern hemisphere in October 2014 as they were in August and September. Large areas of both the North Atlantic and Pacific were above the 98th percentile. There were only limited areas of below average temperatures in the northern hemisphere (parts of the North Pacific to the east of Japan and an area South of Greenland). In the Southern hemisphere, cooler than average sea-surface temperatures were observed in the east Pacific, parts of the South Atlantic and along the southern edge of the Indian Ocean. Large areas of the Southern Ocean were also cooler than average. Warmer than average sea-surface temperatures were observed in much of the Indian Ocean and around the southern fringes of Australia.

According to Rutgers University Global Snow Lab, October snow cover across the Northern Hemisphere was the third highest on record (1967-2014). Northern hemisphere (Arctic) sea ice extent was 8.06 million square kilometres. October 2014 was nominally the 6th least extensive October on record. Southern hemisphere sea ice extent was 19.2 million square kilometres. October 2014 was nominally the 2nd most extensive October on record. 2013 was the most extensive at 19.47 million square kilometres. Sea ice extent data are provided by the National Snow and Ice Data Center in the US.

Last updated: Jan 30, 2015 1:10 PM