Despite a warm spring and year to date, May 2021 was just about average for both temperature and precipitation across the U.S., according to scientists from NOAA’s National Centers for Environmental Information.
But May also brought the first named Atlantic tropical storm of the hurricane season, Ana, near the end of the month.
Below are highlights from our May U.S. monthly climate report:
Climate by the numbers
The average May temperature across the contiguous U.S. was 60.4 degrees F (0.2 of a degree above the 20th-century average), which ranked in the middle third of the 127-year record.
Below-average temperatures covered the northern Rockies, Central and Southern Plains, central Gulf Coast, Southeast and the Ohio Valley. The month saw above-average temperatures across parts of the West Coast, Southwest, New England and Florida.
The average precipitation for May was 2.94 inches (0.03 of an inch above average), which ranked in the middle third of the record.
A soggy setup brought the fifth-wettest May to Louisiana and Texas. California had its fourth-driest May, while Florida and Utah saw their ninth driest.
Meteorological spring and the year to date (YTD)
The average temperature for the contiguous U.S. during meteorological spring (March through May) was 52.6 degrees F (1.7 degrees above the 20th-century average), which ranked in the warmest third of the record. With a precipitation total of 7.53 inches (0.41 of an inch below average), this spring placed in the driest third of the climate record and was the driest since 2006.
The average U.S. temperature for the year to date (January through May) was 44.6 degrees F (1.3 degrees above average) and ranked in the middle third of the record. The first five months of 2021 were also quite dry, with a precipitation total of 11.65 inches — 0.74 of an inch below average — making it the driest YTD since 2012.
Other notable May climate highlights
- Flooding emergency for parts of the Gulf Coast: Slow-moving thunderstorms dropped torrential rainfall across portions of coastal Texas and Louisiana on May 17-18, which resulted in widespread flash flooding, power outages and hundreds of water rescues. More than 1 foot of rain fell near Lake Charles, Louisiana, an area still recovering from damage caused by Hurricanes Laura and Delta last summer.
- Early tropical storm sets record: Tropical Storm Ana formed in the Atlantic Ocean on May 22, making it a record seventh-consecutive hurricane season where at least one named storm formed in the Atlantic Basin before the official start of the season on June 1.
- Drought improved overall, but some states got even drier: According to the U.S. Drought Monitoroffsite link, 43.7% of the contiguous U.S. was in drought, down 4.7% from the end of April. However, drought intensified or expanded across California, Oregon, Washington, the northern Plains, parts of the Great Lakes, Puerto Rico and Hawaii.