Long Island weather forecast: Extreme temperatures this weekend; heat indexes may reach lower 100s through Tuesday

Most of Long Island will see unusually high temperatures early this week as an extreme heat watch takes effect Monday afternoon, according to meteorologists. 

NewsdayTV meteorologist Rich Von Ohlen said the temperature could be record-breaking.

"There's a high likelihood of records being broken across the tristate area, including Long Island, especially Monday and Tuesday, with things settling perhaps by Wednesday," Von Ohlen said.

The National Weather Service on Saturday issued a heat advisory between noon and 8 p.m. Sunday for Nassau and western Suffolk counties.

It will be sunny and in the lower-90s for most of the day on Sunday, but, Von Ohlen said, "moderate-to-high levels of humidity will add to heat and make it feel well over 100 degrees."

The extreme heat watch takes effect at noon Monday afternoon and continues through 8 p.m. Tuesday, according to the weather service.

"We’re looking at heat indexes into the lower 100s," according to Jay Engle, a National Weather Service meteorologist.

There's a "marginal risk" for a severe thunderstorm Sunday, according to the weather service.

An air quality health advisory goes into effect at 11 a.m. Sunday, the Department of Environmental Conservation and State Department of Health announced. The advisory warns of ground-level ozone caused by the heat, sending the Air Quality Index above 100.

The advisory will remain in effect through 11 p.m. Sunday. Ozone levels are generally highest in the afternoon to early evening, according to the advisory, which cautions young children, elderly and people with health issues like asthma to limit outdoor physical activity.

The extreme temperatures is the result of a heat dome, most prevalent in June, July and August. Von Ohlen said. 

The heat dome brings maximum sunlight and dry air, allowing the sun to bake the Earth, Von Ohlen said. It typically lets surface winds to become more westerly. When this occurs, ocean waters no longer cool the Island as they typically would, he added.

An extreme heat watch "means that the combination of heat and humidity could create a dangerous situation in which heat illnesses are possible," according to the National Weather Service advisory.

The watch is in effect for Nassau and western Suffolk counties. The eastern portion of Suffolk, "may end up being on a heat advisory or something like that in a few days, but they’re not on the watch right now," Engle said. 

Sunday's heat index of 78 in Montauk on the eastern tip of Long Island will be 21 degrees cooler than areas of Nassau County where it will be 99, according to the weather service.

The heat index is expected to remain in the triple digits Tuesday and the actual temperature could reach the upper-90s in the western half of Long Island.

Because of the heat, Gov. Kathy Hochul signed legislation Saturday to allow providing refreshments to voters waiting in line cast their ballots on Tuesday. The voting will occur "during a heat wave, with peak temperatures expected to reach the upper 90s and 'feels-like' temperatures ranging from 85-110 degrees statewide," Hochul said in a statement.

Engle said the Weather Service posts "heat safety tips" online, which include things like "never leave young kids in the car alone because they could get heat exhaustion with the windows closed. Use the air conditioners and stay in the shade. Drink plenty of water, even if you’re not thirsty. Wear loose-fit, light-colored clothing."

Cooling centers open

To cope with the heat, the Town of Huntington is making spray parks at Manor Field and Elwood Park free of charge until Thursday. Residents will not be required to show a paid activity card but must show proof of residency. The spray parks in Huntington Station and Elwood will be open from 11 a.m. to 6 p.m. The spray parks will return to regular hours and admission June 26, but may be extended as long as the hot weather lasts, town officials said.

The Dix Hills pool also will be open until 8 p.m. from Saturday through Wednesday.

Beaches at Gold Star Battalion, Crab Meadow, West Neck, Hobart, and Centerport will be open until 8 p.m. with lifeguard. A beach pass is required for Huntington Town residents.

The Town of Huntington also opened its cooling center at Flanagan Senior Center, Monday through Friday until 5 p.m.

Brookhaven Town Supervisor Dan Panico said its three public pools, Centereach, Holtsville and Mastic Aquatic, and its eight beaches, would open this weekend to help residents "beat the heat."

The beaches and pools, which are available from dawn to dusk, were originally to open on June 27.

In addition, all Brookhaven recreation centers and senior centers — at Mount Sinai, New Village in Centereach, Mastic, Moriches Bay, Robt. Reid in Shoreham, St. Michael's in Medford — will operate as cooling centers.

The Town of Smithtown announced on Thursday that its splash parks were now open on weekdays due to the predicted heat wave.

Both parks at Hoyt Farms in Commack and Veteran Memorial Park in St. James open from 11 a.m. to 4 p.m. every day.

Suffolk County residents can check the county website for a full list of municipal cooling centers.

Nassau County Executive Bruce Blakeman said three cooling centers would be open starting on Friday: in Hicksville, Wantagh and Uniondale. These include:

• Cantiague Park administration office, 480 W. John St., Hicksville, 8 a.m. to 6 p.m.
• Wantagh administration building, 1 King Rd., Wantagh, 8 a.m. to 6 p.m.
• Mitchel Field administration building, 1 Charles Lindbergh Blvd., Uniondale, open 24 hours.

Also in Nassau County, residents can cool off at the Town of Oyster Bay Ice Skating Center on Stewart Avenue from 9 a.m. to 11 p.m.

The Town of Hempstead announced the kiddie pools at Veterans Memorial Park Pool in East Meadow; Hewlett Point Park Pool in East Rockaway; and Slate Lane Pool, Acorn Lane Pool and Jerusalem Avenue Pool in Levittown were closed for essential maintenance on Friday, but would be open this weekend.

In light of the hot weather, the Suffolk County SPCA released a list of safety tips for pet owners:

• Animals should never be left alone in a vehicle, even with windows open, as a car can "quickly become a furnace."
• Pet owners should limit their pets' exercise and refrain from letting dogs stand on hot asphalt.
• Tethering a dog outside in temperatures over 90 degrees is against the law in Suffolk.

Newsday's Nicholas Grasso, Miyang Hao, Maureen Mullarkey and Joe Werkmeister contributed to this story.

By Sam Kmack

sam.kmack@newsday.com

Sam Kmack covers the Town of Islip for Newsday. He is a graduate of the University of Southern California and previously worked as a city watchdog reporter in the Phoenix metro area, as well as an investigative journalist at the Arizona Center for Investigative Reporting.