May temperatures each year from 1850-2024 compared to the 20th-century average. It's been several decades since we've had a May that was colder than average (blue bars, below the zero line). May 2024 (final red bar) was the warmest May on record. Mays are getting warmer at a rate of 1.09 ˚F (0.61 ˚C) per century.