Long Island weather: Sunny but cooler

Sunshine but cooler than Wednesday, as the daytime high will top out at 70 degrees: that is the forecast for Thursday on Long Island.

And fine weather, aside from an isolated shower or thunderstorm — and a potentially rainy Saturday — is pretty much what the Island can anticipate through the middle of next week.

"Warmer than average temperatures are forecast to continue for the Great Lakes/Ohio Valley and Northeast/Mid-Atlantic over the next few days," according to the Weather Prediction Center, which is part of the National Weather Service.

And once again, a high pressure system at the surface, combined with "upper level ridging over the eastern U.S. will produce generally dry conditions," the prediction center said.

Falling air in high pressure systems — this one is "centered along the New England coast," the weather service said — dries and cools. So blue skies can result.

Upper level ridging is an elongated area of high pressure at a constant altitude.

Cooler today, but still unusually warm

On Thursday, the weather service said, "Temperatures will be much cooler than Wednesday, but still above normal for most locations except for the immediate coast."

Predicting New York City may see temperatures rise to the mid- to upper 70s, the weather service added: "Across southern Connecticut and Long Island, highs will generally be around 70 degrees."

The mean temperature for Islip during May is 58.6 degrees, according to the weather service. Records for that site begin in 1963.

Night time lows will bounce around the 50s from Thursday to Wednesday.

Friday should offer both clouds and sunshine with thermometers again rising to 70 degrees during the day, the weather service said.

Clouds may roll in that night and the odds of a rainy Saturday are 40%, the weather service advised, as a warm front enters the region. The high for the day should be 74 degrees.

While there is a 30% chance that Saturday night will also see rain, the Sunday to Wednesday stretch should be at least partly sunny.

Sunday likely will be the warmest day of the period, the weather service said.

"Sunday should be a very warm day with highs ranging from 75-80 along south-facing coastlines out east, to the lower 90s in northeast New Jersey," the weather service added.

And then a cold front probably will sweep in late in the afternoon or early evening, which, the weather service said, "should be accompanied by showers and a few thunderstorms, with the better chances inland."

After that, a Canadian high pressure system should help lower temperatures.

Highs during the day on Monday are expected to be 70 degrees, and 68 on Tuesday.

Wednesday probably will be a warmer 78 degrees, as the high pressure system heads out to sea, the weather service said.