Records: October, year-to-date hottest in human history

Select national information (note that different countries report anomalies with respect to different base periods. The information provided below is based directly upon these data):

• The average temperature across Australia during October was +2.89°C (+5.20°F) higher than its 1961–1990 average and the highest departure from average for any month in the country’s 106-year period of record (1282 months), according to the Bureau of Meteorology. This surpasses the previous record of +2.75°C (4.95°F) set two years ago in September 2013. The October average maximum and minimum temperatures for the country were also each record high. The warmth was widespread, with all states and the Northern Territory observing daily average temperatures among their ten warmest for October. New South Wales, Victoria, South Australia, and Western Australia were record warm, with the highest departure from average observed in South Australia, at +4.61°C (+8.30°F).
• It was also warmer than average across most of New Zealand. The national monthly temperature was 0.6°C (1.1°F) higher than the 1981–2010 average for October.
• Norway observed an October temperature that was 1.2°C (2.2°F) higher than its 1961–1990 average. Temperatures in Romsdal and Sør-Trøndelag were about 2–3°C (4–5°F) higher than their averages for October. The air flow patterns that brought the warmer-than-average temperatures are typical of El Niño conditions.
• The capital city of the Faroe Islands, Torshavn, observed its warmest October since 1920, at more than 2°C (4°F) higher than its 1961–1990 average.

With strong El Niño conditions in place, the October global sea surface temperature was 0.85°C (1.53°F) above the twentieth century average of 15.9°C (60.6°F), the highest departure for October on record. This surpasses the previous record set in 2014 by 0.15°C (0.27°F). This margin is larger than the uncertainty associated with the dataset. The October temperature was also the highest departure from average for any month since recordkeeping began in 1880, surpassing the previous record set last month by 0.04°C (0.07°F). Sea surface temperatures during October 2015 were well above the 1981–2010 average across the central and eastern equatorial Pacific Ocean, according to analysis by the NOAA Climate Prediction Center (CPC). Record warm and much warmer-than-average temperatures are notable across the entire region, as shown by the October Temperature Percentiles map above. The CPC expects this El Niño to likely peak during the Northern Hemisphere winter 2015-16 and transition to ENSO-neutral conditions during late spring or early summer 2016. 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.

Other areas across the world’s ocean surfaces also experienced record warmth or much warmer-than-average conditions for October, including the entire Indian Ocean where the Indian Ocean dipole has been positive during all of 2015, along with the central Atlantic Ocean and much of the Arctic Seas. A stretch of the Atlantic Ocean south of Greenland and a region southeast of South America were much cooler than average for the month.

First ten months of 2015
The first ten months of 2015 comprised the warmest such period on record across the world’s land and ocean surfaces, at 0.86°C (1.55°F) above the twentieth century average, surpassing the previous record of 2014 by 0.12°C (0.22°F). This margin is larger than the uncertainty associated with the dataset. To date, eight months this year have been record warm for their respective months. January was the second warmest January on record and April third warmest.

The average global sea surface temperature of +0.71°C (+1.28°F) was the highest for January–October in the 136-year period of record, surpassing the previous record of 2014 by 0.08°C (0.14°F). This margin is larger than the uncertainty associated with the dataset. The average land surface temperature departure from average of +1.28°C (+2.30°F) was also the highest on record for October, surpassing the previous record of 2007 by 0.17°C (0.31°F).

Most of the world’s land areas were much warmer than average, falling within the top 10 percent of their historical temperature range for the January–October period, as indicated by the Temperature Percentiles map above. These regions include South America, Central America, western North America, Africa, most of Eurasia, and large parts of Australia. Record warmth was observed across parts of each of these regions, particularly notable in western North America and much of South America.

The oceans were also much warmer than average across vast expanses, including most of the northern, eastern, and central equatorial Pacific Ocean, the entire Indian Ocean, much of the Atlantic Ocean, and the Arctic waters surrounding northern Europe. All four major ocean basins also had large regions of record warm sea surface temperatures during this 10-month period. In the North Atlantic, a large region south of Greenland remained much cooler than average for the period, with some record cold embedded in that area. Over land, only part of northeastern Canada and the far southern tip of South America were cooler than average during the January–October period.