The calendar may say October but the weather is more typical of January in portions of the western and central U.S.

“A wave of Arctic air has infiltrated the northern tier of the United States this week, shattering record lows, and threatening as many as 70 (other record lows) through Halloween,” AccuWeather said.

Subzero cold was recorded as far south as the Grand Canyon on Wednesday morning, the Weather Channel said. Big Piney, Wyoming, plunged to minus 24 degrees before sunrise Wednesday.

Notorious cold spot Peter Sinks, Utah, dipped to an incredible minus 45 degrees early Wednesday. This appeared to be the coldest October temperature on record anywhere in the Lower 48 states, according to Utah-based meteorologist Timothy Wright.

High temperatures Wednesday were forecast to be 30 to 50 degrees below normal across Colorado, Texas and the central Plains, according to meteorologist Ryan Maue of BAM Weather.

Winter weather outlook: Mild but changeable winter weather predicted for much of US

On Tuesday, the high temperature in Denver only hit 18 degrees, which tied for the coldest October day on record in the city, the National Weather Service reported. About a half-foot of snow added to the wintry feel across the metro area.

Denver’s low temperature Thursday morning could come within a few degrees of the city’s all-time coldest October temperature of minus 2 degrees, the Weather Channel said.

The biting cold air for this time of year is being funneled southward from Canada into the western and central United States by a southward plunge of the jet stream, the Weather Channel reported. That dip in the jet stream will slowly migrate eastward late in the week, taking the colder air with it.

By Friday, while the intensity of the cold will ease, even the Gulf Coast and Eastern Seaboard will see a switch to chilly weather, the Capital Weather Gang said. Highs will hover only in the 50s from Friday through the weekend in cities such as Washington, Philadelphia and New York.

While much of the nation freezes, Florida is seeing record highs on Wednesday, Maue said, with temperatures soaring to near 90 degrees in Orlando, Tampa and Miami.

In California: Infamous ‘Diablo’ winds are fueling fierce northern California wildfires.

This article originally appeared on USA TODAY: Winter weather in October: Arctic cold breaks records in Utah, Denver