Warm, summerlike weather is coming to Long Island. But its arrival is being detained by a slow-moving rain system that’s escorting in some cooler air, the National Weather Service said Monday.

Showers and possible thunderstorms are in the picture for Monday afternoon and most of Tuesday, the service’s Upton office said.

Monday’s mostly sunny morning will give way to increasing clouds and the chance for isolated showers and possibly thunderstorms, News 12 Long Island meteorologist Bruce Avery said.

Avery said if showers or storms pop up, they will be “more likely in the late afternoon, say from 4 p.m. to sunset.”

Daily highs Monday stay in the mid to upper 60s, with winds from the east at 5 to 10 mph.

Tuesday looks to be wet, too, before winds shift and usher in warm air from the southwestern United States, the service said. Daily highs on Wednesday in the mid 80s are possible, marking a jump of nearly 20 degrees.

Expect rain Monday night into Tuesday morning, with precipitation amounts to a half-inch possible, the service said.

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Tuesday morning also opens with the chance of showers, and thunderstorms also are possible after noon. Daily highs in the mid to upper 60s are likely.

Tuesday night calls for gradual clearing, with the start of the warm air and drier conditions.

Daily highs Wednesday will be in the low to mid 80s; Thursday and Friday highs are in the low to mid 70s, the service’s Upton office said.