Friday likely will be the last rainy day before the sunshine returns to dominate the Saturday to Monday period, the National Weather Service in Islip said.
An urban and small stream flood advisory has been issued through 11:15 a.m. for Nassau and western Suffolk counties.
As of 10:20 a.m., the weather service said radar indicated heavy rain that will cause flooding. Up to one inch of rain has already fallen and up to one inch more is expected, the weather service said.
And the weather service said: "Despite a good deal of cloud cover for much of today, it remains warm and rather humid."
It added, "Dew point readings will reside in the upper 60s well north, with lower and a few middle 70s further south and east making it feel uncomfortable again."
No heat index warnings were issued, though Friday will be a rather warm summer day.
"Temperatures should make it into the middle 80s across most areas this afternoon, with southeastern coastal sections a few degrees cooler with a sea breeze later in the afternoon," the experts predicted.
Saturday should be bright and clear with a high of 86 degrees during the day.
Sunday should be another fine, slightly warmer day, with a daytime high just below 90 degrees, the weather service said.
Monday will be a close twin with temperatures creeping up to 91 degrees during the day.
While there is a 30% chance of rain after midday on Tuesday, Wednesday looks like a delightful day to hit the beach. Highs are predicted to be in the mid to upper 80s, the weather service said.