The average temperature for the six-month period was 0.85°C (1.53°F) above the 20th century average of 15.5°C (59.9°F), surpassing the previous record set in 2010 by 0.09°C (0.16°F). The average global sea surface temperature of +0.65°C (+1.17°F) for the year-to-date was the highest for January–June on record, surpassing the previous record of 2010 by 0.04°C (0.07°F). The average land surface temperature of +1.40°C (2.52°F) was also record high, surpassing the previous record of 2007 by 0.13°C (0.23°F), according to NOAA’s National Centers for Environmental Information.

Most of the world’s land areas were much warmer than average. These regions include nearly all of Eurasia, South America, Africa, and western North America, with pockets of record warmth across these areas. All of Australia was warmer than average. The combined average temperature over global land and ocean surfaces for June 2015 was the highest for June on record, at 0.88°C (1.58°F) above the 20th century average of 15.5°C (59.9°F). Records date back to 1880.

June 2015 marks the third month this year that has broken its monthly temperature record, along with March and May. The other months of 2015 were not far behind: January and February were each second warmest for their respective months and April was fourth warmest.

The average Arctic sea ice extent for June was 350,000 square miles (7.7 percent) below the 1981-2010 average and 60,000 square miles larger than the smallest June sea ice extent on record that occurred in 2010. This was the third smallest June extent since records began in 1979 according to analysis by the National Snow and Ice Data Center using data from NOAA and NASA.

Antarctic sea ice during June was 380,000 square miles (7.2 percent) above the 1981-2010 average. This was the third largest June Antarctic sea ice extent on record and 140,000 square miles smaller than the record-large June extent of 2014.

The Tokyo Climate Center – which uses slightly different observations - said the global average surface temperature in June 2015 was +0.76°C above the 20th century average.