(Bloomberg) -- For generations, trick-or-treaters across much of the US have faced a dilemma: wear a jacket and ruin the effect of their costume, or forgo the coat and freeze. But this year’s Halloween across much of the Mid-Atlantic and Northeast will be different with near-record heat forecast from Philadelphia to New York to Boston.
“I went to a Halloween party this weekend and one of our friends was wearing one of those inflatable suits. They said, ‘It’s actually pretty nice in here with the fan blowing on me,’” says Torry Dooley, a meteorologist with the National Weather Service in Boston, which is expected to reach 81F (27C) on Halloween. “So maybe you just need to wear one of those.”
After weeks of persistently dry weather, a ridge of high pressure is parked over the eastern US this week. The result will likely be a hot, breezy and bone-dry Halloween. That won’t just make revelers sweat; it’s also increasing wildfire risk in parts of Massachusetts, Rhode Island and Connecticut.
“These temperature anomalies for Halloween in the northeastern US are 20 to 25 degrees above average,” says Andrew Orrison, a meteorologist with the US Weather Prediction Center in College Park, Maryland. He adds that heat will extend down to the Gulf Coast, too.
The warmest Halloween ever recorded in much of the Northeast was in 1946. In New York’s Central Park, temperatures hit 81F that year while they reached 81F in Boston and 82F in Hartford, Connecticut. This year will come close, with temperatures set to reach into the upper 70s in New York. This month is also in the running to become the driest October in recorded history in Central Park.
Boston will come “within striking distance” of the Halloween record, Dooley says, with highs predicted to hit 79F at Logan International Airport, which sits on the coast, and edge closer to 80F further inland. Hartford is expected to tie its historic record. Even Salem, Massachusetts, which sits closer to the water, is likely to see Halloween highs in the upper 70s as an inland mass of warm air blows eastward across the village.
The unusually warm Halloween is triggered by a persistent high-pressure system holding warm air over the region. Orrison said scientists can't draw a direct link between this specific weather pattern and human-caused climate change without deeper studies. But global warming is boosting background temperatures, making heat records more likely.
Nationwide, fall temperatures have warmed an average of 2.5F since 1970, according to data from Climate Central. Nights have warmed even faster, particularly in the Northeast. New York City and Boston have seen October nighttime temperatures rise 4F while Philadelphia’s October nights have warmed nearly 6F since 1970.
That’s having an impact beyond Halloween costume choices: The increasing weather volatility that accompanies climate change is making it hard for small businesses like apple orchards and pumpkin patches to plan, said Claudia Schmidt, assistant professor of marketing and local and regional food systems at Penn State. “This can be a cost burden for agritourism operators because they have expenses like musicians, food trucks and vendors, and when visitors don’t show up, their profits can take a hit.”
In the US West, Halloween will be wet and cool, with rainy weather settling in from the Pacific Northwest to Northern California, Orrison says, and a storm system arriving on the day of Halloween that could bring heavy rainfall in some areas and snow at higher elevations.
The pattern that’s raised temperatures and blocked moisture across the eastern US isn’t expected to break until mid-November. Until then, the odds remain tilted in favor of unseasonably warm weather.
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