Monthly Report Summary Information

Global Summary Information - September 2012

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Global temperature ties with 2005 as record highest for September

Arctic sea ice retreats to all-time minimum,
while Antarctic sea ice expands to all-time maximum

The globally-averaged temperature for September 2012 tied with 2005 as the warmest September since record keeping began in 1880. September 2012 also marks the 36^th consecutive September and 331^st consecutive month with a global temperature above the 20^th century average.

Most areas of the world experienced much higher-than-average monthly temperatures, including central Russia, Japan, western Australia, northern Argentina, Paraguay, western Canada, and southern Greenland. Meanwhile, far eastern Russia, western Alaska, southern Africa, parts of the upper midwest and southeast United States, and much of China were notably below average.

In the Arctic, sea ice extent averaged 1.39 million square miles, resulting in the all-time lowest September sea ice extent on record, and on September 16^th, the Arctic reached its all-time lowest daily extent on record. More than 4.57 million square miles of ice was lost in 2012, the size of the entire United States and Mexico combined. Conversely, on the opposite pole, Antarctic sea ice reached its all-time highest daily extent on record on September 26^th.

September 2012 Selected Climate Anomalies and Events

Global temperature highlights: September

• The combined average temperature over global land and ocean surfaces for September tied with 2005 as record highest for September, at 60.21°F (15.67°C) or 1.21°F (0.67°C) above the 20^th century average. The margin of error associated with this temperature is ±0.20°F (0.11°C).

September 2012 Blended Land & Sea Surface Temperature Anomalies in °C
• September marked the 36^th consecutive September and 331^st consecutive month with a global temperature above the 20^th century average. The last below-average September was September 1976 and the last below-average month was February 1985.
• The global land temperature was the third warmest September on record, at 1.84°F (1.02°C) above the 20^th century average of 53.6°F (12.0°C). The margin of error is ±0.45°F (0.25°C).
• Higher-than-average monthly temperatures were most notable across central Russia, Japan, western Australia, northern Argentina, Paraguay, western Canada, and southern Greenland, while temperatures were below average across far eastern Russia, western Alaska, southern Africa, parts of the upper midwest and southeast United States, and much of China.
Australia experienced its third warmest September maximum temperatures since records began in 1950, with the nationally-averaged temperature 3.49°F (1.94°C) above the 1961–1990 average.
The monthly-averaged daily, maximum, and minimum temperatures all were above normal across Argentina, particularly in the central and northern regions of that country. Record-high September minimum temperatures were observed across parts of midwestern Argentina.
Following its second warmest summer since national records began in 1900, monthly temperatures remained above average across Hungary during September, ranging from about 1.8°F to 6.3°F (1.0°C to 3.5°C) above the 1971–2000 average.
• For the ocean, the September global sea surface temperature was 0.99°F (0.55°C) above the 20^th century average of 61.1°F (16.2°C), tying with 1997 as the second warmest September on record. This was also the highest monthly global ocean temperature departure from average for any month since May 2010. The margin of error is ±0.07°F (0.04°C).
• Borderline neutral / weak El Niño conditions were present during September across the central and eastern equatorial Pacific Ocean, with sea surface temperatures close to 0.9°F (0.5°C) above average for a three-month period, the official threshold for the onset of El Niño conditions. According to NOAA's Climate Prediction Center, those conditions are expected to continue into the Northern Hemisphere's winter 2012/13, possibly strengthening into a weak El Niño warm phase during the next few months.

Polar ice highlights: September

• According to the National Snow and Ice Data Center, September 2012's Arctic sea ice extent averaged 1.39 million square miles, which was 48.7 percent below the 1979–2000 average for the month and 16 percent below the previous record low extent in September 2007.


Arctic and Antarctic sea ice extent, from the September 2012 Global Snow & Ice Report
• Arctic sea ice reached its annual minimum extent on September 16 at 1.32 million square miles, marking the smallest Arctic sea ice extent in the 34-year period of record. The occurrence of the annual minimum extent marked the end of the 2012 melt season, during which 4.57 million square miles of ice was lost (the size of the entire United States and Mexico combined)—the largest annual sea ice loss on record for the Arctic.
• On the opposite pole, Antarctic sea ice reached a record maximum extent. The September average Antarctic sea ice extent was 7.49 million square miles, slightly larger than the previous record large extent in 2006. On September 26, the Antarctic sea ice reached its annual maximum extent at 7.51 million square miles, making it the largest daily Antarctic sea ice extent on record.

Precipitation highlights: September

• Seasonal rainfall in western and central Africa was unusually heavy during September, leading to flood conditions that stretched from Senegal eastward to Chad.
• The southwest Asian monsoon stalled over northwestern India before beginning its annual withdrawal, bringing excessive rainfall to most of the region during the month of September. According to the India Meteorological Department, the heavy rainfall brought seasonal precipitation totals to within the normal range and alleviated drought conditions for much, but not all, of the country.
• Several countries in eastern Europe, including Romania, Hungary, Bulgaria, and Poland, endured drought during September. Hungary experienced one of its worst droughts in two decades.

Global temperature highlights: Year to Date

• Record to near-record warmth over land from April to September and increasing global ocean temperatures in the eastern equatorial Pacific Ocean resulted in the first nine months of 2012 ranking as the eighth warmest such period on record, with a combined global land and ocean average surface temperature of 1.03°F (0.57°C) above the 20^th century average of 57.5°F (14.1°C). The margin of error is ±0.18°F (0.10°C).

Year-to-date temperatures by month, with 2012 compared to the five warmest years on record
• The January–September worldwide land surface temperature was 1.69°F (0.94°C) above the 20^th century average, marking the sixth warmest such period on record. The margin of error is ±0.40°F (0.22°C).
• The global ocean surface temperature for the year to date was 0.77°F (0.43°C) above average and ranked as the 10^th warmest such period on record. The margin of error is ±0.07°F (0.04°C).