Long Island weather: Another sunny day, with highs in the 70s

Thursday should offer just about ideal weather for anyone who likes sunny skies, a high near 75 degrees during the day and a light breeze topping out at 11 mph.

There is, however, a 30% chance of showers, mainly after 11 p.m. The same odds of rain will prevail on Friday, mostly before 2 p.m., the National Weather Service said.

The switch from sunny to cloudy and damp is driven by a high pressure system moving out to sea, the weather service said. And then, it said, "a coastal low pressure system lifts north towards Long Island."

Air falls to Earth in high pressure systems, drying and cooling, so they bring clear skies. Warm, rising air in low pressure systems, however, can allow vapors to form rain drops.

"Light rain showers will be possible tonight and into early Friday but with preceding dry conditions, high pressure to the northeast, and our positioning under and upper-level ridge, widespread showers do not appear likely," the weather service said. A ridge is an elongated area of high pressure.

The chances of showers slip to 20% on Saturday — again, most likely before 2 p.m. — and then the rest of the weekend and on into Monday should be clear.

The weather service predicted the chances of rain on Tuesday are 30%, and the odds rise to 40% on Wednesday.

Minor flooding possible

Friday’s daytime high will be 76 degrees, the weather service predicted, and Long Islanders can expect daytime highs in the upper 70s to low 80s through Wednesday.

In contrast, the weather service's Weather Prediction Center warns more "excessive heat" awaits the Northwest and northern California on Saturday. Already, wildfires have consumed half a million acres in 11 states, according to the National Interagency Fire Center, which coordinates U.S. wildland fire programs.

And before the weekend, much of the Upper Midwest and then the Southeast are at risk of powerful storms and flooding, starting Thursday.

Back on Long Island, Nassau’s South Shore residents Thursday and Friday night may see minor flooding, the weather service said, due to "increasing astronomical tides and long period swells."

While Saturday night may be cloudy, look for a bright and sunny Sunday, as a new high pressure system moves in.

"Global models are in good agreement with an anomalously strong upper level ridge expanding westward across the Atlantic and into the eastern U.S.," the weather service said.

While coastal areas will remain cooler, the weather service said, "What is clear and with high confidence is an increasingly warmer, humid airmass (will be) building in through the weekend into early next week."

It added, "Highs will get up into the upper 80s/lower 90s by Sunday from New York City and points north and west, with the lower to mid-80s closer to the coast."