42-hour wind chill warning takes effect 6 p.m. Sunday

Bitterly cold air to blow in Saturday night

Bitterly cold air is poised to blow into Wisconsin Saturday night and stick around through Wednesday morning.

The cold front that will bring the air mass in will move through Saturday morning and could bring some light snow along with strong winds. For this reason, the National Weather Service has issued a winter weather advisory — mainly for blowing snow — that is in effect until 9 a.m. Saturday for areas from Madison to the south.

Once the front comes through, temperatures will slowly fall on Saturday and end up below zero by Sunday morning, with wind chills already reaching as cold as minus 25 degrees. Temperatures will only rise a few degrees early in the day before crashing once more, leading to wind chills as cold as minus 30 degrees Sunday afternoon. There will be a wind chill advisory in effect from midnight to 6 p.m. Sunday as a result of the wind chills below minus 20 degrees.

After that, things really get cold.

Temperatures will drop near to minus 25 degrees by Monday morning with breezy conditions. Wind chills will range from minus 40 degrees to minus 55 degrees during the coldest part of the day.

Highs on Monday will still be in the double digits below zero and wind chills will be as cold as minus 40 degrees, even in the afternoon. Lows drop back near minus 20 degrees on Tuesday morning, with wind chills once again falling to between minus 30 degrees and minus 45 degrees.

Because of the extreme conditions, a wind chill warning will take effect at 6 p.m. Sunday and last through noon on Tuesday. Wind chill warnings are issued when wind chills are expected to be below minus 35 degrees for at least three consecutive hours.

With wind chills this low, frostbite can occur to exposed skin in as little as 10 minutes, and hypothermia is likely if proper precautions aren’t taken, including wearing clothing in layers and limiting time outdoors.

The stretch of subzero weather is poised to be the coldest stretch the Madison area has seen since Feb. 1 through 4, 1996, when Wisconsin saw four consecutive days with highs below zero and lows colder than minus 16 degrees each day. 

The last time Madison had a low below minus 20 degrees was on Dec. 25, 2000, when the low reached minus 21 degrees.