Climate Change

		Departure of temperature from average for last month (updated by the 17th of each month) from the National Climatic Data Center.
		Average March arctic sea ice coverage as observed by satellites between 1979 and 2009. Image credit: National Snow and Ice Data Center.

The globe recorded its sixth warmest October since record keeping began in 1880, according to NOAA's National Climatic Data Center. NASA's Goddard Institute for Space Studies rated October 2009 as the 2nd warmest October on record, falling 0.06°C short of the record set in 2005, while the UK < a href=http://hadobs.metoffice.com/hadcrut3/diagnostics/global/nh+sh/monthly>HADCRUT3 dataset rated October the 7th warmest (this dataset does not include most of the Arctic, Antarctic, and Africa, where there are few land stations). NOAA rated the year-to-date period, January - October 2009, as the fifth warmest such period on record. The October satellite-measured temperatures for the lowest 8 km of the atmosphere were 6th - 7th warmest on record. Global ocean Sea Surface Temperature (SST) anomalies were the 5th warmest on record.

Third coldest October for the U.S.

For the contiguous U.S., the average October temperature was 4.0°F below average, making it the 3rd coldest October in the 115-year record, according to the National Climatic Data Center. The cold was centered in the Midwest, where Oklahoma had its coolest October on record and ten other states had their top five coolest such months.

Wettest October on record in the U.S.

The nationwide precipitation of 4.15 inches was nearly double the long-term average of 2.11 inches. Three states (Iowa, Arkansas, and Louisiana) saw their record wettest October. Fourteen other states had precipitation readings ranking in their top five category. Only three states (Florida, Utah, and Arizona) saw below normal precipitation. Arkansas continued its remarkable run of wetness in 2009. The state has seen four months with top three precipitation ranks this year (May, 1st wettest; July, 3rd wettest; September, 2nd wettest; October, 1st wettest). As a result, the state's year-to-date average is the wettest in 115 years of record keeping. This contrasted with persistent dryness in Arizona, which saw its second-driest year-to-date period.

U.S. drought

At the end of October, 12% of the contiguous United States was in moderate-to-exceptional drought. This is the second-smallest drought footprint of the decade, based on the U.S. Drought Monitor. Major drought episodes in California and South Texas improved significantly. Drought conditions emerged across much of Arizona. About 45 percent of the contiguous United States had moderately-to-extremely wet conditions at the end of October, according to the Palmer Index (a well-known index that measures both drought intensity and wet spell intensity). This is the largest such footprint since February 2005.

U.S. fire activity

October, like September, saw below-normal fire activity in all respects. A total of 3,207 fires burned about 158,000 acres in October, according to the National Interagency Coordination Center. Each of these values is below this decade's average for October.

Strong El Niño conditions develop

El Niño conditions continue over the tropical Eastern Pacific. Ocean temperatures in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", were at 1.8°C above average on November 15, just above the 1.5°C threshold for a strong El Niño, according to the Australian Bureau of Meteorology. NOAA's Climate Prediction Center is maintaining an El Niño Advisory. Current conditions and model forecasts favor continued strong El Niño conditions during the Northern Hemisphere Winter 2009-10.

October sea ice extent in the Arctic 2nd lowest on record

October 2009 Northern Hemisphere sea ice extent was the 2nd lowest since satellite measurements began in 1979, according to the National Snow and Ice Data Center (NSIDC). Only 2007 saw lower arctic sea ice extent. During the first two weeks of November, arctic ice extent decreased below the 2007 record minimum.