Climate bulletin - November 2017
Summary of the world's climate in November 2017
Global land and sea-surface temperature
The global average temperature for November 2017 as estimated from the HadCRUT.220.127.116.11 data set was 0.55±0.13°C above the 1961-1990 average. Globally, November 2017 was most likely the tenth warmest November on record although, given the uncertainties, it could lie anywhere between 2nd and 17th warmest. Global temperature data sets maintained by NASA GISS, NOAA NCEI, Berkeley Earth and C3S also show that November was a warm month globally. November was nominally between 3rd and 5th warmest in these data sets, comfortably within the HadCRUT4 uncertainty range. Differences between the data sets were due mainly to exceptional warmth in the sparsely observed Polar Regions. Sea-surface temperatures east of the dateline in the Tropical Pacific were mostly below average. La Niña conditions were established in November.
The global average land temperature for November 2017 was 0.88±0.26°C above the 1961-1990 average. For global land areas, November 2017 was nominally the 10th warmest November on record and very likely one of the top twenty. Unusual warmth – defined as temperatures exceeding the 90th percentile for the month – was recorded across: northeast Russia and western Alaska; western parts of the conterminous US (four states – Arizona, Colorado, New Mexico and Utah - had their warmest November on record) and parts of Mexico; northern parts of South America; limited areas of western Africa; an area to the north and east of the Black Sea; islands in the southwest Indian Ocean; southern India; and areas of southern Australia. Bahrain had its warmest November on record, tied with 1954. The Arctic was also rather mild in November with temperatures at a number of long-term stations exceeding the 98th percentile. Svalbard Airport reported a monthly-average temperature that exceeded the 1961-1990 average for the 84th consecutive month.
Few areas were unusually cold – defined as regions experiencing temperatures below the 10th percentile. These were: small areas of eastern Canada, a small area in northeast Russia, Hawaii and a limited area of northwest Australia. Although there were larger areas of below-average temperatures in Canada and northeast Russia, these anomalies were not unusual in the historical context except in a few limited areas.
The global average sea-surface temperature (SST) for November 2017 was 0.43±0.09°C above the 1961-1990 average, nominally the 5th warmest on record and very likely between the 2nd and 15th warmest. Sea surface temperatures in the equatorial Pacific east of the dateline were mostly below average with SSTs in parts of the eastern Tropical Pacific falling below the 2nd percentile of the 1961-1990 distribution. La Niña conditions were established in November.
Areas of unusually warm SST included: large areas of the North Atlantic, extending north into the Norwegian Sea; areas of the Indian Ocean; and the western Pacific. An area of high pressure over New Zealand, not unusual during La Niña, saw exceptionally high SSTs in the Tasman Sea with daily SSTs exceeding 6°C above average in some areas. Two warm bands around 30°N and 30°S in the Pacific which have been a persistent pattern, were still evident in November. Areas of unusually low SST included limited areas of: the eastern Tropical Pacific, the South Atlantic, eastern Indian Ocean, the eastern coast of Greenland.
Higher than average precipitation totals (based on the monthly first-guess analysis by the Global Precipitation Climatology Centre, GPCC) were recorded in: northwestern US and southwest Canada; parts of northwest, central and northeastern Russia; western Alaska; a band running from Norway south to Greece and Italy; an area crossing coastal areas of eastern Algeria, Tunisia and western Libya; areas across Tropical Africa; central Pakistan; a band running south to north across central Australia; parts of the Maritime Continent, Tonga and Fiji were also wetter than average, which is typical for La Niña; Madagascar; and southern Brazil amongst others. A storm which developed on 12 November, brought high winds and/or heavy rain to parts of France, Italy, Corsica, Sicily, Greece and the Balkans. The heavy rain in Greece also led to flooding and loss of life. The storm briefly developed tropical storm characteristics including high winds and an eye-like structure; such storms when they occur in the Mediterranean are sometimes termed Medicanes.
Drier than average areas included: southern and southeastern parts of the US; much of Mexico and other parts of Central America; northern parts of Brazil, and northern Argentina; Spain, Portugal (in Portugal it was the 8th consecutive month of below average precipitation and the 2nd driest Autumn; France was also unusually dry during Autumn ); much of New Zealand (some locations were the driest in more than 100 years); parts of southern Africa including Gabon, Botswana, Namibia and South Africa.
South-eastern China, parts of Vietnam (Typhoon Damrey made landfall in Vietnam in early November), and northern parts of the Philippines were wetter than average. To the northwest of this wetter area was a band of drier than average conditions, which extended across Myanmar, parts of China, South Korea and southern parts of Japan.
One Tropical Storm, Rina, formed in the North Atlantic in November. Activity in the 2017 Atlantic hurricane season was above average with 17 named storms (long-term average 12), 10 hurricanes (long-term average 6) and 6 major hurricanes (long-term average 3).
Based on data from the HadISST.18.104.22.168 data set and from the National Snow and Ice Data Center, the Northern Hemisphere (Arctic) sea ice extent in November 2017 was likely to have been between the 3rd and 6th least extensive in the satellite record. There is some uncertainty in the ranking as a number of years have similar extents.
Southern Hemisphere (Antarctic) sea ice extent was nominally between the 2nd and 7th least extensive November on record. Sea-ice extent in the Antarctic has been low since late last year. For more details and analysis of the ice extents including updates throughout the summer, see the sea-ice monitoring brief.