The weekend in southwestern Connecticut starts on a sunny, hot note -- with sketchy air quality -- but could storm to an end.

Saturday will have bright skies as the temperature rises to a high in the mid-80s, with a south wind 5 to 14 mph, according to the National Weather Service.

An air-quality alert has been issued by state health officials from 11 a.m. to 11 p.m. Saturday because the combined heat and humidity could trigger unhealthy ozone levels.

Saturday night will be partly cloudy, with a low temperature in the mid-60s.

On Sunday, there is a slight daytime chance of showers and thunderstorms after noon, and some of the storms could produce gusty winds and heavy rain, the NWS warns. Otherwise, skies will be mostly sunny, with a high temperature near 80 degrees. Chance of daytime precipitation is 20 percent.

By Sunday night, the odds of precipitation increase to 60 percent, the NWS warns in a "hazardous weather outlook." The isolated storms could be severe, triggering downpours and strong winds. Overnight, the low temperature dips to the mid-60s.

On Monday, more showers are likely -- and possibly a thunderstorm. Skies will be cloudy, with the temperature rising to a high in the mid-70s. Chance of daytime precipitation is 60 percent. Monday night, although more rain is possible, the odds decrease to about 30 percent, the NWS says. The overnight low temperature will be in the mid-50s.

Tuesday should be mostly sunny, with a high temperature in the low-70s. Nighttime will be clear as the temperature dips to a low in the mid-50s.

The outlook for Wednesday, according to the weather service, is sunny and temperatures in the 70s.