Extremely hot weather across southwestern Connecticut today -- the peak of the current heat wave -- is expected to produce scorching heat index readings of between 105 to 110 degrees, the National Weather Service warns.

The "excessive" heat warning for the region is in effect from 11 a.m. to 10 p.m., says the NWS. Because of the stagnant, humid air mass enveloping the area, an air-quality alert has also been triggered.

The actual daytime high temperature is expected to rise into the high-90s, perhaps even hit 100, and combined with high humidity, it could feel like it's 110 degrees.

Tonight should be mostly clear, with a low around only in the mid-70s.

Tomorrow will be a bit cooler, according to the NWS, with temperatures in the low- to mid-90s. There also could be isolated showers and thunderstorms after 11 a.m. Skies will be partly sunny, a north wind between 3 and 11 mph. There remains a slight chance of showers and thunderstorms tomorrow night, with a low temperature in the mid-70s.

A cooling trend is expected to continue Sunday, with high temperatures in the mid- to upper-80s. There is a slight chance of showers and thunderstorms before noon. Sunday night will be partly cloudy, with a low around 66 degrees.

Monday is expected to be partly sunny, with a high near 79 degrees. But Monday night, a chance of showers and thunderstorms is possible, and the temperature is expected to dip to a low around 67.

Tuesday should be mostly sunny, with a high near 82, the weather service predicts.