Long Island weather: Heat advisory issued for Wednesday, chance of severe thunderstorms

If you thought Tuesday was warm, brace yourself. 

A heat advisory will be in effect from 11 a.m. to 8 p.m. Wednesday for parts of Long Island, New York City, Westchester and Rockland counties, and northeast New Jersey. Maximum heat index values will be in between 95 and 101 in these areas, creating hot and humid conditions, according to the National Weather Service.

The heat index is a measure of how hot it really feels when relative humidity is factored in with air temperature.

With it comes increased risk of heat-related illness for vulnerable populations, the service said.

For Long Island, the advisory focuses on northern Nassau County, where it could feel as warm as 96 degrees, but the service warns that it could expand to include more zones if temperatures trend a few degrees warmer.

Areas outside the advisory can expect heat index values ranging from 93 degrees in Stony Brook to 84 in Montauk, and are still advised to exercise caution such as avoiding prolonged exposure or physical activity. Both can increase the risk of heat stroke, cramps and exhaustion.

A cold frontal passage Wednesday afternoon also brings a marginal risk of severe thunderstorms into the evening. Damaging wind gusts up to 60 mph are possible.

The rain should move out by 2 a.m. Thursday and temperatures should drop to a high near 78 and a low of 62, according to the service.

Friday is expected to be dry and mostly sunny with a high near 77.

Rain does threaten Labor Day weekend, with a 40% chance of showers Saturday and a 30% chance Sunday. 

Monday, however, should be partly sunny with a high near 80.