May 20—Southern Maine has seen one of its cloudiest Mays in years, according to data collected by the National Weather Service. And there’s still more than a week to go.
By Tuesday evening, this month had already seen more cloudy days than the previous five Mays, said meteorologist Greg Cornwell. Twelve days were considered “cloudy,” five “partly cloudy” and three “clear,” according to weather service archives.
“With the assumption today will rate as cloudy, 2025 ties 2019 in recent years for number of cloudy observations. We will likely exceed that in the coming days,” Cornwell wrote in an email Tuesday evening. “Looking back further, 2017 had 14 days rated cloudy. So we are currently running the cloudiest month of May for the past eight years based on data from the Portland Jetport.”
Forecasters at the weather service station in Gray observed more than 50% sky coverage by clouds nearly every afternoon, including total coverage on 10 days, according to archived data. That figure is captured at about 4 p.m. daily.
With more clouds, southern Maine has also seen relatively high rainfall levels this month, Cornwell said.
“We certainly started off (the month) with a wet start,” he said on an afternoon phone call. “It’s been a gloomy appearance.”
Twelve of the first 19 days in May saw at least some rain — usually less than half an inch — reported at the Portland International Jetport, according to weather service data.
So far, 4.65 inches of rain have fallen over the jetport. That’s well over the monthly average of 3.48 inches and nearly three times the total rainfall of 1.7 inches last recorded May, Cornwell said.
“The last May it was this wet was also 2017 with 5.94 (inches) for the whole month,” he wrote.
Cornwell said a number of weather systems moving slowly across New England have brought cooler temperatures to low-altitude regions. Those systems help keep the atmosphere moist and the skies overcast, he said.
That trend is likely to continue over the next few days, as a rainy system is expected to move across southern Maine beginning Thursday and would likely clear up by Saturday, ushering in a relatively dry and warm start to next week, he said.
“It’ll be kind of short-lived Monday and Tuesday, and maybe we’ll get more moisture,” Cornwell said. But he noted that it was too early to say for sure, as there are “still plenty of solutions that could go either way, dry or wet.”
Keeping an eye on the long weekend, Cornwell said temperatures in the White Mountains in New Hampshire will be notably colder than in regions closer to sea level and urged hikers to plan for potentially shifting conditions. Below-freezing wind chills and snow accumulation are both likely at elevations above 3,000 feet, he said. That’s just over the halfway point of Mount Katahdin, Maine’s highest point, with an elevation of 5,269 feet.
“The higher summits of the White Mountains will probably be getting wintry conditions through this period,” Cornwell said. “It’ll kind of feel like late spring, early summer down at sea level, but you get elevated and wind conditions get cooler fairly quick.”
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