Record-breaking cold spell forecast for parts of the U.S. on Halloween

Trick-or-treaters can expect frightening temperatures on Halloween this year, forecasters said. 

Record-breaking cold could set in across portions of the U.S. as October comes to an end, according to the National Weather Service. A "potent" cold front is set to move through the Gulf Coast and the East Coast states by Monday night.  

"It may be a good idea to figure out how to incorporate a jacket into that costume tomorrow night across much of the lower 48," the National Weather Service said in a social media post. "'Mr. Freeze' is a good costume, but only if it's intended."

Which parts of the U.S. will see below average temperatures?

Most of the central and eastern U.S. will see below average temperatures on Tuesday and Wednesday, Dr. Rick Knabb, a meteorologist with The Weather Channel, said. 

"Temperatures will be cold enough on Halloween night for most of the eastern two thirds of the country that jackets will be required — unless you can strategically wear warm layers underneath your costume to stay warm," the meteorologist said.

The Plains, Midwest and parts of the Tennessee Valley and Appalachians will see the coldest temperatures on Halloween itself, Knabb said. The forecast shows temperatures in those areas will be 20 to 30 degrees Fahrenheit below average for the time of year. 

Expect temperatures to be about 10 to 20 degrees below average just above everywhere else east of the Rockies, Knabb said.

"Record cold low (and cool high) temperatures are expected through Thursday morning from Texas northeastward into the Ohio and Tennessee Valley regions, and even for some spots along the East Coast from South Carolina to Maine," Knabb said.

How long will the cold last?

The cold spell is expected to last through Thursday, Knabb said. Temperatures will be near average in most areas by Friday or the weekend. 

Freeze watches and warnings have been issued for the week from central Arizona through the southern Plains and into the Midwest and Ohio Valley, according to the National Weather Service. The organization issues a freeze watch when there's potential for significant, widespread freezing temperatures within the next 24-36 hours. 

More than 100 million people will see below freezing temperatures on Tuesday morning and the number will soar to 165 million people on Thursday morning, Knabb said. 

Is there any rain, wind or snow in the Halloween forecast?

There could be rain or snow showers in the Upper Midwest, Great Lakes and interior Northeast through Wednesday, according to the National Weather Service. Parts of the Midwest will also deal with "blustery COLD winds."

Northern Maine may see accumulating snowfall, forecasts show. Snow squalls are possible across parts of the Northern Plains, Upper Midwest and the Great Lakes through Halloween.