Heavy rain, as well as thunderstorms, are likely today, the National Weather Service warns.

In a "Hazardous Weather Outlook" issued early today, the weather says that downpours of 1 to 2 inches an hour are possible, which could trigger flash flooding in southwestern Connecticut.

The greatest threat of storms comes after 4 p.m., the NWS predicts, with a daytime high temperature about 70 degrees and a south wind 8 to 11 mph. Chance of precipitation daytime precipitation is 60 percent.

Tonight, storms with heavy rain are likely as the temperature falls to a low of about 60 degrees, with a south wind 5 to 9 mph. Odds of nighttime precipitation are about 80 percent.

Showers and thunderstorms remain a threat tomorrow, again with heavy rainfall possible. The high temperature is expected to be in the mid-60s; chance of daytime precipitation is 80 percent.

Tomorrow night is likely to see more showers, as the temperature falls to a low of about 50 degrees. Nighttime precipitation odds are about 80 percent, the NWS says.

And the holiday weekend is also expected to begin on a wet and cool note, with Saturday showers in the offing and a high temperature reaching only about 60 degrees. Cloudy skies and breezy conditions will also prevail; odds of daytime precipitation are 80 percent. More showers are possible Saturday night, the NWS says, with an overnight low temperature in the upper-40s.

On Sunday, the likelihood of rain eases, with daytime odds of about 30 percent, and a high temperature about 60 degrees. Nighttime will be partly cloudy with a low temperature in the upper-40s.

Monday, Memorial Day, has the brightest outlook for the weekend, as the weather service predicts sunny skies and temperatures in the upper-60s.