The month of May typically signals both an ending and a beginning: The waning days of spring and then the time-honored leap into summer vacation season. Before we throw on our bathing suits and flip flops, let’s first take a look back at how last month, spring and the year to date fared in terms of the climate record:
Climate by the numbers
Last month, the average contiguous U.S. temperature was 60.6 degrees F — 0.4 degrees above the 20th-century average — ranking near the middle of the 123-year period of record. Parts of the West and Southeast were warmer than average with near- to below-average temperatures in parts of the Central and Eastern U.S., according to scientists from NOAA’s National Centers for Environmental Information.
The average precipitation total for May was 3.31 inches, 0.40 inch above the 20th-century average and tying with 2009 as the 25th wettest on record. Above-average precipitation fell across most of the East and parts of the Rockies and Great Plains.
The average spring (March-May 2017) temperature across the contiguous U.S. was 53.5 degrees F, 2.6 degrees above average, making it the 8th warmest spring on record. From the Rockies to East Coast, most of the seasonal warmth occurred during the early and middle parts of spring.
The average spring precipitation total was 9.39 inches, 1.45 inches above average, making this spring the 11th wettest on record.
Year to date
The year to date (January through May 2017) average temperature for the contiguous U.S. was 47.0 degrees F, 3.7 degrees above the 20th-century average. This YTD period was the second-warmest on record for this period.
The YTD precipitation total was 14.85 inches, 2.46 inches above average, making it the third-wettest January-May on record.
Other notable climate events and facts included:
Record rains in the U.S. East, South: Record and near-record May precipitation fell in the Northeast, Mid-Atlantic, Mississippi Valley and central to southern Appalachians. Record flooding was observed in the mid-Mississippi Valley.
Florida remains tinder dry: Continued dryness in Florida caused drought to expand and intensify, prompting large wildfires across central and northern areas of the Sunshine State.
A record-breaking Wisconsin tornado: An EF-3 tornado tracked 83 miles across northern Wisconsin on May 16 resulting in one fatality and 25 injuries. This was one of the longest-track tornadoes in the state’s history.
Continued drought relief: On May 30, 5.3 percent of the contiguous U.S. was in drought, up slightly from early May. Drought improved in the Northeast, Mid-Atlantic and Southeast. Drought worsened in the Northern and Southern Plains and in Florida.
Washington State had a cool start to year: Washington was the only state cooler than average for January to May.
Coastal flooding events rose markedly last year: An update to NOAA’s annual report of high-tide flooding (sometimes referred to as nuisance flooding) found that among most of the cities studied, flooding increased in 2016 by 130 percent on average since the mid-1990s and continues to accelerate.
For WeatherNation: Meteorologist Mace Michaels