Long Island weather: Ideal Father's Day on tap; rain, possible flooding forecast for Monday

The summer solstice arrived early Sunday, bringing with it an idyllic Father's Day that comes with a stormy weather warning for Long Island Monday afternoon, forecasters say.

The solstice arrived at 4:24 a.m. EDT in the Northern Hemisphere Sunday as the Earth’s axis reached its maximum tilt toward the sun. The longest day of the year is expected to be a pleasant summer day, with a high of 80 and sunny skies, the National Weather Service said. The overnight low will be in the mid-60s.

But forecasters say rain is likely to arrive Monday afternoon with cooler temperatures and a high of 75. By Monday night, the chance of showers reaches 90%.

A "pretty potent system" is developing and heading toward Long Island, according to Matt Wunsch, a meteorologist at the National Weather Service in Upton.

The rain will be heaviest beginning Monday afternoon and into the evening.

There’s still "a little uncertainty" about whether the storm will be prolonged or more scattered, Wunsch said, but either way, the region can expect some "pretty intense rainfall rates," with around 1 to 1.5 inches expected across much of the island.

The heavier rain brings with it a "chance of flash flooding," Wunsch added, although the weather service is not predicting widespread flooding.

Tuesday's forecast calls for a chance of continuing rain, but Wednesday and Thursday should be sunny, with temperatures around 80 and dropping to the mid-60s at night, the service said.

Check back for updates on this developing story.