Saturdays' splendid weather — sunny, with a high of 64 degrees and light breezes not expected to top 10 mph — should help offset the rainy and windy Sunday that the National Weather Service in Islip expects.
The first to feel Sunday's rain could be any all-night partiers and the earliest risers: there is a 30% chance it will start after 4 a.m., the weather service said.
Sunday's forecast includes possible thunderstorms after midday, with as much as two inches of rain in some areas. Though the high will reach 65 degrees, the weather service said, the wind will clock in at 22 mph, with gusts hitting 36 mph.
The weather service warned of coastal flooding for Suffolk and Nassau, though the timing differs, with Nassau's advisory beginning and ending earlier.
For southern Nassau, the advisory runs from 6 a.m to 10 a.m. For northwestern Suffok and northern Nassau, the timing is 9 a.m. to 1 p.m.
One to two feet of flood waters are predicted for both regions. Breaking waves along Nassau's oceanfront could reach three to five feet, and moderate flooding and beach erosion around high tides can be expected, the weather service said.
Sunday's stiff breezes, shifting to the west and then the northwest, should drive out the storm.
"Skies will clear during Sunday night and remain mainly clear into much of Monday," the weather service said, when the thermometer should hit 63 degrees during the day, falling about 10 degrees at night.
Those same temperature swings prevail for much of the week.
In both Nassau and Suffolk, the weather service warned: "Additional minor coastal flooding is possible over multiple high tide cycles Monday and Tuesday."
Drizzling rain could return on Tuesday: the odds were assessed at 30% by the weather service, and the temperature again will be be a bit warmer than usual at 64 degrees.
Cloud-lovers will delight in Wednesday's forecast, as the sun could be largely obscured, the experts said.
Both Thursday and Friday have the same odds of showers: 30%, according to the weather service.