With hot and humid conditions Tuesday, the National Weather Service has issued a Heat Advisory and an Air Quality Alert for most of Connecticut.

Fairfield, northern Middlesex and New Haven counties will have unhealthy air with elevated levels of ozone.

The Heat Advisory was issued because the heat index will reach between 93 and 97 degrees. Peak temperatures are expected between 1 and 5 p.m., according to the NWS hourly forecast.

A Heat Advisory is issued when the combination of heat and humidity is expected to make it feel like it is 95 to 99 degrees for two or more consecutive days, or 100 to 104 degrees for any length of time.

The heat advisory is in effect from 10 a.m. to 9 p.m.

Although Litchfield County is not included in the heat advisory, temperatures will still me in the low 90s Tuesday.

On Monday high temperatures were 94 at Bradley International Airport in Windsor Locks, 93 at Sikorsky Memorial Airport in Stratford; 91 at Tweed-New Haven Airport in East Haven; 90 at White Plains airport, near Greenwich; and 89 in Danbury.

With the extreme heat and humidity, seniors and those with chronic health problems or mental health conditions are at an increased risk. The NWS says homes without air conditioning can be much hotter than outdoor temperatures. “Use air conditioning to stay cool at home, or go to a place that has air conditioning. Check on vulnerable friends, family members and neighbors,” it says.

The oppressive heat and humidity will break on Wednesday when a cold front moves in. The NWS said the front could bring in thunderstorms with heavy rain and gusty winds.

The forecast

Today: Sunny, with a high near 93. Heat index values as high as 97. Light south wind increasing to 5 to 10 mph in the morning.

Tonight: Mostly clear, with a low around 71. South wind 6 to 8 mph.

Wednesday: A 50 percent chance of showers and thunderstorms after noon. Some of the storms could produce gusty winds and heavy rain. Mostly sunny, with a high near 87. South wind 3 to 7 mph.

Wednesday Night: Showers and thunderstorms likely before 11pm, then a chance of showers. Some of the storms could produce gusty winds and heavy rain. Mostly cloudy, with a low around 68. Southwest wind around 5 mph becoming calm in the evening. Chance of precipitation is 60 percent. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Thursday: Mostly sunny, with a high near 86. North wind 3 to 6 mph.

Thursday Night: Mostly clear, with a low around 64.

Friday: Mostly sunny, with a high near 85.