Climate

Islip weather by month

Average highs, lows, rain and snow for every month, from 30 years of weather records.

Average temperatures

Best time to visit: May, July, September, when highs are mild and rain is lightest.

Month	High	Low	Rain	Snow	Wet days
January	39°F	25°F	3.7 in	10.3 in	11
February	41°F	26°F	3.3 in	9.4 in	10
March	48°F	32°F	4.5 in	6.5 in	11
April	58°F	41°F	4.1 in	0.60 in	11
May	68°F	51°F	3.3 in	0.00 in	12
June	77°F	61°F	4.0 in	0.00 in	10
July	83°F	67°F	3.3 in	0.00 in	9
August	81°F	66°F	4.2 in	0.00 in	9
September	75°F	59°F	3.6 in	0.00 in	9
October	64°F	47°F	4.0 in	0.00 in	9
November	54°F	38°F	3.4 in	0.50 in	10
December	44°F	30°F	4.7 in	4.5 in	12

NOAA U.S. Climate Normals 1991–2020, Islip Li Macarthur Ap, Ny Us (9.7 mi away, 84 ft). Wet days: days with at least 0.01 in of precipitation.

What is the hottest month in Islip?

July, with an average high of 83°F and low of 67°F.

What is the coldest month in Islip?

January, with an average low of 25°F and high of 39°F.

When does it rain most in Islip?

December is the wettest month, averaging 4.7 in of precipitation; the year totals about 46.1 inches.

Does it snow in Islip?

Yes. Snowfall averages about 32 inches a year, mostly in January and February.

What is the best time to visit Islip?

For mild weather (highs between 65°F and 85°F) with the least rain, May, July, September.

Where do these numbers come from?

NOAA’s 1991–2020 U.S. Climate Normals for the Islip Li Macarthur Ap weather station, 9.7 miles from downtown: 30-year averages, not a forecast.