Close to 2 inches of rain could fall in Shelton between now and Christmas morning, with the heaviest rain expected on Wednesday afternoon and evening.
Temperatures also will climb into the upper 50s, so any hopes for a white Christmas in Connecticut will have to wait for another year.
The National Weather Service (NWS) said the rain should begin again late tonight, and become steadier during the day on Wednesday, which is Christmas Eve.
The rain will continue Wednesday night, with strong winds, possible thunderstorms and an overnight low in the 50s, the NWS said.
On Christmas Day, the rain should end around 8 a.m. It will become sunnier, but winds could gust up to 33 mph, according to the NWS. The daytime high could reach 56 degrees.
In upstate Connecticut, the NWS has issued a Flood Watch due to the expected rain. Up to 2.5 inches is possible in Litchfield County and other areas.
Future days: Colder temps, possible snow
The NWS forecast for Shelton for future days is:
Friday: Sunny, with a high near 48. At night, partly cloudy and a low around 32.
Saturday: Mostly sunny, with a high near 50. At night, mostly cloudy and a low around 31.
Sunday: A chance of rain and snow, with a high near 44. It could also snow at night, with a low around 27.
Monday: A chance of snow, with a high near 37. Snow also is possible at night, with a low around 24.