Mostly nice weather is ahead for Long Islanders planning outdoor activities or heading to the beach Sunday with more warm temperatures predicted and some areas expecting highs near 90 degrees. But there is a slight chance those venturing into the heat could get a cool off, courtesy of a few raindrops.

Expect “warm traditional summer weather with humidity and warm temperatures” on Sunday, said News 12 Long Island meteorologist Bruce Avery.

There’s a 20-percent chance of showers or a thunderstorm “pretty much all day – at no specific hours,” said John Murray, a meteorologist with the National Weather Service at Upton.

Faye Barthold, also a meteorologist with the Upton office, said temperatures Sunday and for most of the week will be above the normal high of about 82 at Islip.

Avery said Sunday’s high in Patchogue will be 80 and the high in Southold and Kings Park will be 81. It will be warmer in Montauk and Wantagh where highs will be 83 and 87 respectively.

Sunday night, temperatures are expected to drop to 72.

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On Monday there will be a mix of sun and clouds with the possibility of more wet weather and a high soaring to 89 in most areas with 90 predicted for Islip. A low of 73 is forecast.

“There’ll be a cold front approaching from the west, so for Monday — especially in the afternoon — you’ll see a slight chance of showers and thunderstorms as it moves across the region,” Murray said.

Tuesday will be mostly sunny with a high of 87 and a low of 67 — and again with rain possible.

“There’s a slight chance of showers and thunderstorms in the morning then that front will move off shore,” Murray said. “Tuesday night will be dry.”

Things cool off a bit for Wednesday when mostly sunny skies and a high of 81 and low of 67 is forecast.

“Again there will be dry weather conditions as high pressure starts building in from the west keeping the weather dry,” Murray said.

For Thursday the mostly sunny skies continue along with dry weather.

“The dry weather continues with the weather still controlled by a high pressure system lingering across the region,” Murray said. “The high pressure starts to move off shore by Thursday night.

The high Thursday will be 85 and the low 70.

Hazy sunshine is in the forecast for Friday when a high of 87 is expected with a low of 72.