Long Island weather forecast: 'Deadly' heat could last through July 4

Temperatures could feel above 100 degrees for four consecutive days this week, including on Independence Day, during Long Island’s first heat wave of the summer, the National Weather Service said.

The weather service had initially warned of extreme heat lasting from Wednesday to Friday. But forecasters said Monday those sweltering temperatures will last through the evening of Saturday, the Fourth of July.

The next few days have “potential to be a multiday extreme heat event with near record high temperatures and little overnight relief,” the weather service said in a Monday afternoon advisory. The high heat “can be deadly for those without adequate cooling and hydration,” the agency added.

Some areas on Long Island, particularly those in Nassau County and even in western Suffolk County, could see temperatures reach above 90 degrees on Wednesday, according to weather service meteorologist Brian Ciemnecki. But for “the majority of the Island,” he said, the heat wave — or three consecutive days during which temperatures reach at least 90 — will begin on Thursday and continue into the weekend.

Long Islanders should limit their time outside, take frequent breaks in the shade if they must work outdoors, stay hydrated, check on seniors and others who are vulnerable and remain in air-conditioned areas, the weather service said. Anyone with underlying illnesses and visitors from cooler climates are among those “especially” at high risk of heat exhaustion or heat stroke.

High temperatures will reach either side of 90 degrees on Wednesday before soaring into the mid- and upper-90s on Thursday, Friday and Saturday, according to the weather service. Heat index values, or the “feels like” temperatures, could hit 109.

A “slight chance” of thunderstorms is forecast for Tuesday and Wednesday evenings as well as Friday afternoon, Ciemnecki said. There is “at least a chance” for showers every day this week, including Saturday, he added.