Long Island weather: Sunny and breezy

Sunshine, a high during the day of 64 degrees and a breezy northwest wind are what Long Islanders can expect Thursday, the forecasters said.

"A good deal of sunshine is expected through today, with temperatures likely to be just a few degrees below normal," the National Weather Service said.

And Friday should be mostly sunny, though a few degrees cooler, according to the weather service, thanks to a high pressure system.

Rain may reach Long Island after midnight Friday, however.

And there is a 30% chance of showers, mostly after 8 a.m. on Saturday, as a low pressure system and cold front arrive from the Ohio and Tennessee valleys, according to the weather service and its Weather Prediction Center.

High pressure systems can produce blue skies, as air tends to dry and cool as it falls to Earth. Low pressure systems, in contrast, allow rain drops to form as the air cools as it rises.

That trough, or low pressure system "pivots" through Long Island late Saturday afternoon, the weather service predicted.

"This will bring any chance of showers to an end by evening and maybe by late in the day," the weather service said.

It added, "Any precipitation for early in the weekend is expected to be light," and clouds should clear away Saturday night.

Thermometers on Saturday will rise no higher than 57 degrees, the weather service said — a pattern of cool weather that will be shared by broad swathes of the Midwest and Northeast.

"Behind the cold front, cool and below average temperatures will be found throughout much of the eastern U.S. over the next couple of days," the prediction center said.

It added, "Highs will only reach the 50s and 60s across the Great Lakes, Ohio Valley, Mid-Atlantic, and Northeast."

The prediction center estimated temperatures will run as much as 10 to 20 degrees below average.

Clouds should roll back in on Sunday, the weather service said.

The high for the day should be 62 degrees.

Monday, thanks to a low pressure system, likely will be rainy. The odds of showers are 60%, according to the weather service.

The daytime high on Monday should be about 60 degrees.

And then look for the sunshine to rule the skies on Tuesday and Wednesday as a high pressure system from the Great Lakes dominates.

Highs during the two days should reach the low 60s, the weather service said.