Long Island weather forecast: High heat, humidity hang on into weekend

Extreme weather was forecast for Long Island on Friday, with brutal heat and heat index values that could make it feel like it's more than 100 degrees outside, along with possible thunderstorms.

The National Weather Service issued a heat advisory for Nassau and Suffolk, to remain in effect through 8 p.m. Saturday, warning: "Heat and high humidity may cause heat related illnesses." And mid-morning the weather service issued an air quality alert, in effect until 11 p.m. Friday.

Air quality monitoring site AirNow.gov said ground-level ozone readings were expected to surpass 100 on Friday, creating an unhealthy air quality situation for "sensitive groups," which include people with lung disease such as asthma, as well as children, teens and older adults who are routinely active outdoors for more than six hours daily. That alert covers all of Long Island, as well as the five boroughs and Westchester and Rockland counties.

As of 10:30 a.m. the AirNow website was still monitoring other air pollutants in the "moderate" range, with area ozone levels listed as "Good."

The weather service forecast painted an oppressive weather picture for Friday and Saturday, with possible patchy fog and showers both days.

Sunday should be filled with sunshine, with a high of 90 degrees coupled with a light breeze.

A heat advisory is issued when the combination of heat and humidity is expected to make it feel like it is between 95 and 99 degrees for two or more consecutives days, or between 100 and 104 degrees for any length of time. On Friday, that combination could make it feel like it's 101 degrees.

That combination also has the weather service warning vulnerable Long Islanders — seniors, those with chronic health problems or mental health conditions — to use air conditioning or go to a location that has air conditioning.

The weather service also advised limiting outdoor work if possible, noting the Occupational Safety and Health Administration "recommends scheduling frequent rest breaks in shaded or air conditioned environments." Staying hydrated also is a must.

Forecasters were calling for a high of 90 degrees Friday, followed by a high of 89 on Saturday.

There was a moderate rip current risk along all South Shore ocean beaches from Queens to Montauk on Friday, the weather service said, with the possibility of "life threatening rip currents."

By John Valenti

john.valenti@newsday.com

John Valenti, a Newsday reporter since 1981, has been honored nationally by the Associated Press, Society of the Silurians and National Headliner Awards for investigative, enterprise and breaking news reporting, as well as column writing. He is the author of “Swee'pea,” about New York playground basketball star Lloyd Daniels. His debut crime novel, “For Nothing Is Hidden,” rooted in 1950s Long Island, was released in October 2025.