The coldest air in North America is coming to New York and Boston for Thanksgiving, and driving up power prices in the Northeast.

Temperatures will plummet across the region, with the low in Central Park dropping to 18 degrees Fahrenheit (-8 Celsius) late Wednesday, and the high Thursday hitting just 26, the National Weather Service said. Boston’s low will be 21 degrees, the coldest on record for the date going back to the 1870s.

Winds gusts of up to 28 miles per hour, meanwhile, will make it tough for the big balloons at Macy’s Thanksgiving Day Parade in Manhattan.

“The coldest air in the Northern Hemisphere right now is in Canada and that’s what’s coming,” said Rob Carolan, owner of Hometown Forecast Services. “The wind is an issue for the balloons. It will be blowing right down Fifth Avenue.”

Power demand jumped Wednesday morning as the Thanksgiving chill began to descend on New England. Electricity consumption is well above forecast, according to grid operator ISO New England. Wholesale electricity in Boston for delivery at 8 a.m. Thursday rose 8.6 percent to $128.89 a megawatt-hour, the highest for that hour since January.

Meanwhile, spot natural gas prices for delivery into New England cities, including Boston, have more than doubled this week to more than $13 per million British thermal units, according to Bloomberg Natural Gas Composite prices.