Two warm fronts, one that's arrived in southwestern Connecticut this morning and another moving in overnight, will bring humid and much warmer-than-normal air for the time being.

Today, expect sunshine and shirtsleeve weather through the afternoon, according to the National Weather Service. But unstable air accompanied by a low-pressure system that will pass to the north later will produce clouds, a chance of rain and a possible thunderstorm overnight.

The shower activity will pretty much be over by daybreak tomorrow, but temperatures will remain above normal and the air will feel muggy.

On Wednesday, a strong low-pressure system will move from the Mississippi Valley north to Ontario, dragging behind it a cold front that will arrive sometime later that day. Forecasters are not in agreement on how long this front will linger over southwestern Connecticut. Still, most expect there will be showers and thundershowers Wednesday afternoon and into the evening.

Thursday and Friday should be cooler and partly sunny.

The sun will set today at 5:57 p.m., with 10 hours and 42 minutes of sunlight. The waning moon will rise tonight at 7:21 p.m. Sunrise on Tuesday will occur at 7:17 a.m.

High tide today will be at 1:05 p.m. in Bridgeport and 1:08 p.m. in Stamford/Greenwich.

Here's more details in the forecast from the National Weather Service:

Today: A slight chance of showers and thunderstorms after 3 p.m. Partly sunny, with a high near 66 degrees. Southwest wind between 3 and 10 mph. Chance of precipitation is 20 percent.

Tonight: Showers and thunderstorms likely, then showers and possibly a thunderstorm after midnight. Low around 58 degrees. South wind around 10 mph. Chance of precipitation is 90 percent. New rainfall amounts between one-half and three-quarters of an inch possible.

Tuesday: A chance of showers, mainly before 9 a.m. Cloudy, then gradually becoming mostly sunny, with a high near 69 degrees. South wind between 7 and 10 mph. Chance of precipitation is 50 percent. New rainfall amounts of less than one-tenth of an inch possible.

Tuesday night: A chance of showers, mainly after midnight. Mostly cloudy, with a low around 59. South wind around 9 mph. Chance of precipitation is 40 percent.

Wednesday: A chance of showers, then showers likely and possibly a thunderstorm after 2 p.m. Cloudy, with a high near 71. Southwest wind between 11 and 13 mph. Chance of precipitation is 60 percent. New rainfall amounts between one-tenth and one-quarter of an inch, except higher amounts possible in thunderstorms.