[A flooded parking lot with a car partially submerged in high waters in front of a local business in Lake Charles, Louisiana, after slow-moving thunderstorms dropped more than a foot of rain on May 17, 2021. Image from NOAA NWS Forecast Office Lake Charles, LA.]

[Written from NOAA and NOAA NCEI]  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. Precipitation was above average from the central and western Gulf Coast into portions of the central Plains and scattered across parts of the northern Rockies and southern New England.

California had its fourth-driest May, while Florida and Utah saw their ninth driest. Precipitation was below average across much of the West, portions of the northern Plains, Great Lakes, northern New England, mid-Atlantic and Southeast.

According to the June 1 U.S. Drought Monitor report, 43.7 percent of the contiguous U.S. was in drought, down about 4.7 percent from the end of April. Drought intensified and/or expanded across California, Oregon, Washington, the northern Plains, parts of the Great Lakes and across Puerto Rico and Hawaii. Drought emerged across portions of the eastern Carolinas and Virginia. Drought severity lessened across portions of the Rocky Mountains and Northeast and drought was mostly eliminated across the central and southern Plains.

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.

Edited for WeatherNation by Mace Michaels