WESTPORT — A blast of Arctic-like air is gripping southwestern Connecticut this morning, propelling a sharp drop in temperatures with windchill values clocking below zero.

The high temperature today is expected to remain below 20 degrees, according to the National Weather Service, with northwest winds of 10 to 20 mph triggering windchills around 0 at the coast and 0 to minus-10 in the interior.

In a “Special Weather Statement” issued early this morning, the NWS warns:

“If you need to be outside, be prepared for the wind and cold, and dress in layers and wear a hat, heavy coat, as well as gloves or mittens. 

“Frostbite can occur in a short amount of time, so dress in layers and make sure all exposed skin is protected.”

By tomorrow, temperatures are predicted to rise to a more seasonal level in the mid-30s under mostly sunny skies.

The intervening days are forecast to be largely the same, until Friday night, when the temperature again plunges below 10 degrees and rises to a high of only 20 degrees Saturday.

In reaction to the cold snap, Gov. Ned Lamont — for the first time this year — directed the state’s severe cold weather protocol to be activated through tomorrow at noon.

“The purpose of the protocol is to ensure that the most vulnerable populations receive protection from the severe cold conditions, which could be life threatening if exposed to the elements for extended periods of time,” according to an announcement from the governor’s office.

Anyone in need of assistance because of the extreme cold should call “2-1-1,” the announcement said.