Today will be another hot day on Long Island, but by afternoon the humidity level should decrease as dew points drop into the low to mid 60's. Tomorrow will again be a hot day, but clouds will be on the increase in the afternoon. At this time, it appears that any rain should hold off until Saturday night.
An extended period of unsettled weather is likely for Long Island from Saturday night until Tuesday morning. This is due to an unseasonably south latitude polar jet orientation with multiple short waves moving through the northeast in a northwest flow, which is a pattern that often offers very little predictability.
The first batch of rain looks to be from late Saturday night into Sunday late morning. There is a chance that Sunday afternoon is mostly dry before more showers arrive Sunday night into Monday. By Tuesday afternoon, drier air should be working into the area, and Wednesday now appears to be the best day of the week with low humidity levels and temperatures slightly below normal.
This map shows the projected rainfall amounts only through 2 PM on Monday according to the NAM model:
Image from tropicaltidbits.com