By John Schwing

WESTPORT — The pre-Christmas weather outside will turn frightful Thursday afternoon, heralding the holiday with a potentially dangerous mix of heavy rain, strong winds, coastal flooding and even thunderstorms, according to warnings issued by the National Weather Service.

After the meteorological mayhem clears from southwestern Connecticut by Friday night, the region will plunge into a deep freeze expected to last through the middle of next week.

Eversource, meanwhile, is gearing up for the storm, which could trigger widespread power outages.

But, if the forecast is accurate, there is only a slight chance snowflakes will fall, so a white Christmas is likely to remain the stuff of holiday ballads and sugarplum dreams.

The harsh reality of the forecast, however, has triggered a “Hazardous Weather Outlook” for Westport and the rest of southwestern Connecticut from Thursday afternoon through Friday night, according to the weather service.

Rain is expected to start falling about 4 p.m. Thursday, as breezy winds start gusting up to 25 mph and temperatures rise into the balmy high-40s.

Overnight, the storm will intensify, with the NWS forecasting downpours and wind speeds near 50 mph, prompting a “Wind Advisory” from 10 p.m. Thursday through 10 p.m. Friday. Temperatures, however, will rise to the decidedly un-wintry low-50s.

The unsettled conditions may trigger thunderstorms early-morning Friday.

The onslaught also has prompted the weather service to issue a “Coastal Flood Warning” for the area from 8 a.m. through 1 p.m. Friday.

Rain is expected to continue most of Friday as temperatures drop sharply, with the Fahrenheit falling to the low-20s by late afternoon and dropping more steeply to about 10 degrees overnight into Saturday.

The stark change in temperatures may bring a chance of snow mixing with the precipitation later Friday. However, there is expected to be no accumulation in this area.

Strong wind gusts, some as high as 45 mph, will continue through most of Friday.

The storm is expected to clear out Saturday morning and sunny, breezy conditions should prevail, but the temperature is expected to rise no higher than the mid-20s. Overnight, the temperature will be about 10 degrees.

Sunday, Christmas Day, also should be sunny, clear and very cold with high readings in the 20s.

Sunny skies are forecast through mid-week, although the daytime high temperature will not rise above the freezing mark until Wednesday, according to the NWS.

Emergency information

A list of emergency contact information for Westport, assembled by the local Emergency Management Team, can be found here.

Power outages can be reported online at Eversource.com or by calling 800-286-2000. Customers who signed up for the power company’s two-way texting feature can send a text to report an outage and receive outage updates as they happen.

John Schwing, the Westport Journal consulting editor, has held senior editorial and writing posts at southwestern Connecticut media outlets for four decades. Learn more about us here.