New York City was forecast to hit 78 degrees (25.5 Celsius) on Halloween, with Boston expected to top out 76 degrees (24 Celsius). Caribou, Maine, was expected to hit a high of 70 degrees (21 Celsius), well above the Halloween average of 47 degrees (8 Celsius).
By 2 p.m., several locations around the city had started to hit or tie records.
Buffalo, New York, was on track for a record-breaking high of 75 degrees (24 Celsius) - a year after light snow fell on Halloween.
Meanwhile in Maplewood, New Jersey, it was beach weather along Maplewood Avenue during one of the best costume parties in the region.
"These temperatures are running on average about 20 degrees warmer than normal," said Samantha Borisoff, a climatologist at the Northeast Regional Climate Center at Cornell University. She noted that weather can vary widely in October, a transitional month between seasons.
"So every Halloween can be very different," she said.
This year was a far cry from 2011, when an early Nor'easter just before Halloween dumped heavy, wet snow around New York's Hudson Valley region. In 2012, the New York City area was reeling on Halloween after Superstorm Sandy ravaged the northeastern coastline on Oct. 29, causing about $65 billion in damage.
Elsewhere, parts of eastern Minnesota and northwestern Wisconsin were getting their first snow of the season Thursday. The National Weather Service said there was high uncertainty about accumulations because the ground is still warm. Snow melted when it hit the pavement in downtown Minneapolis.
But revelers in the Northeast should enjoy the treat while it lasts. Temperatures were expected to return to normal ranges starting Friday.
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