The National Weather Service has issued several flood warnings for parts of Connecticut and forecast thunderstorms and rain for Sunday.

In addition, a flood warning has been issued for the southern part of Fairfield County, effective from 10 p.m. Sunday to 1 a.m. Monday, the weather service said.

The weather service said it would rain most of the day, with thunderstorms possible before 2 p.m. and possibly after 3 p.m. The chance of rain in the state is 70 percent, the NWS added. Although “precipitation amounts of less than a tenth of an inch” are forecast, more precipitation could occur in the event of thunderstorms, the weather service said.

In the afternoon, the Boston office of the weather service reported that there could be “some sunshine” on Sunday despite the “heavy cloud cover”.

Highs are expected to be just below or near 80 degrees, and winds should not exceed 11 mph for most of the day, NWS said. Lows could drop to 68 degrees during the overnight hours.

The weather service said more precipitation is expected during the overnight hours and fog may develop by Monday morning. The agency said the fog should have cleared by 11 a.m., but the rest of Monday will likely be cloudy and rainy again, with the possibility of thunderstorms.