Is summer arriving early? Find out if May is warming up where you live.
As another sultry air mass surges up the Eastern Seaboard this weekend, May is picking up where April left off – with summer-like temperatures and even some humidity.
According to the calendar, summer doesn’t start until June 20, but long-term temperature trends suggest it will start feeling like summer sooner.
The nation’s capital experienced nine days with temperatures at or above 80 degrees last month. That ties the third-highest number of such days since records began in 1936 at the Reagan National Airport.
Farther north, there were a dozen days in New York in April when the temperature reached at least 70 degrees, the highest number since 2010. In Tampa, 11 days had temperatures at or above 90 degrees, more than double the previous record.
The U.S. wasn’t alone. A record-breaking heat wave in parts of Asia and the Middle East set temperatures soaring toward 120 degrees. In Ireland, the temperature nearly reached 79 degrees, the country’s record-highest April reading. The United Kingdom had its warmest start to May on record, almost reaching 85 degrees.
Will these unusually warm conditions continue into May? And is the month trending warmer with time? The answers depend on where you live.
Is May getting warmer where you live?
Over the last 40 years, average temperatures during May have increased for 90% of counties across the contiguous states.
Amid a nationwide warming trend, only a section of the Rockies and northern Plains has cooled.
These states have warmed the most:
- Washington, 1.8 degrees
- Pennsylvania, 1.5
- Tennessee, 1.4
- West Virginia, 1.3
- Ohio, 1.3
- Vermont, 1.3
- Massachusetts, 1.3
- New York, 1.2
- Kentucky, 1.2
In D.C., May has warmed by around 0.6 degrees since 1985. Baltimore has warmed by 1.3 degrees, New York by 0.8 degrees and Los Angeles by 0.4 degrees.
Several counties in Washington state have warmed the most, led by Chelan County to the east of Seattle.
In a warming climate, seasons are changing. Summer is expanding, and winter is contracting. That means many places will experience summer-like temperatures earlier and more frequently than before.
How this May is shaping up
Warmer-than-average conditions are forecast to continue for much of the country during May, especially during the second half of the month.
The warmth will initially be somewhat tempered by wet and stormy conditions in southern, central and eastern states, as well as in D.C.
This change toward more unsettled weather will come with more clouds after one of the clearest starts to spring on record. It may also come with the risk for more flooding in the southern Plains, particularly next Tuesday, an area that experienced flash flooding this week.
Meanwhile, some of the clearest and warmest parts of the country through the first half of May will be the northern Rockies, northern Plains and Upper Midwest.
Areas from Eastern Washington to Minnesota look to be among the most unusually warm in the country.
In California and the Southwest, temperatures will lack consistency, oscillating from above to below average and back again in the coming weeks.
Humidity in the air
Summer-like levels of humidity recently infiltrated the nation’s capital and will continue into early next week.
Muggy air from south-central states is blowing eastward and will be felt as far north as New York this weekend.
It won’t be humid every day, but waves of sultry air will bubble northward from a warmer-than-average Gulf of Mexico throughout the month.
Last summer was exceptionally humid across the United States, contributing to the most humid summer ever recorded globally. This long-term rise in atmospheric moisture is driven by the fact that a warmer atmosphere can hold more water vapor. Water vapor is a powerful greenhouse gas – it traps heat and amplifies warming, which allows the air to hold even more moisture. This creates a positive feedback loop that further intensifies humidity and global warming.
While May will certainly feature warm and humid weather, a few cooler, cloudy interludes will remind you that the season is still spring.