Another steamy day is forecast for southwestern Connecticut today, with temperatures in the mid- to upper-90s.

It will "feel" even hotter, according to the National Weather Service, with a heat index registering at 100 degrees or higher.

The high heat and humidity have prompted to state officials to issue an "air-quality" alert from 11 a.m. to 11 p.m. today because conditions are expected to generate unhealthy ozone levels.

Skies will be mostly sunny, and there will be a southwest wind 8 to 13 mph.

Tonight will be partly cloudy with the temperature sipping to the mid-70s and a west wind 5 to 9 mph.

Tomorrow, the heat wave is expected to break later in the day, with a colder air mass moving into the region that should trigger scattered showers and thunderstorms, mainly after 1 p.m. The NWS warns that some of the storms could produce small hail, gusty winds and heavy rain. Before the storms, the temperature is expected to rise to the low-90s.

Showers and thunderstorms are likely overnight tomorrow and, again, the weather service warns that some of the storms could be severe. The low temperature will fall to the low-70s overnight.

On Thursday, there is a slight chance of showers and thunderstorms in the morning. The skies are expected to clear by afternoon as the temperature rises to the mid-90s. There is also a slight chance of showers Thursday night, and the temperature will dip to the mid-60s.

The outlook for Friday, the NWS says, is partly sunny with a high temperature near 80 degrees.