The US National Oceanic Atmospheric Administration (NOAA) compiled the following about key measurements for May:
May 2023 was the third-warmest May since records began to be kept in 1850, or 174 years ago inclusive.
The year-to-date (January–May) surface temperature of Earth was the fourth warmest of “such period” on record.
The US National Center for Environmental Information (NCEI) is “virtually certain (> 99.0%)” that 2023 will rank as one of the top ten warmest years on record with an 89% chance of ranking in the top five.
Ocean temperature hit a record global high for May, marking its second consecutive record-breaking month, when compared with 1985–1993.
Amid unusually high May temperatures in North America, Canadian wildfires burned more than 6 million acres in late May and early June, causing widespread deterioration of Canadian and US air quality.
Though Africa, Asia, and Europe each had a “top-20 warmest May,” Oceania’s May was cooler-than-average—the coolest May for the region since 2011.
Antarctica, too, had a “cooler-than-average May.”
The Arctic, on the other hand, experienced its fifth-warmest May on record.