Weather in Long Island, New York for September 2026
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So far, September 2026 in Long Island shows a warmer trend than usual by 2.7 °F.
Expect cooler weather in the next days in Long Island with the forecast suggesting a temperature of 21.1 °F, lower than the historical average.
In general, the average temperature in Long Island at the beginning of September is 24.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 20.9 °F by the end of September.
Long Island experiences moderate rainfall in September, with an average of 10 rainy days and a total precipitation of 122.9 mm.
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Long Island Weather September
Temperatures trend during September in Long Island
September weather in Long Island day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Moderate rain at times | 26° /19° | 24 mm | 4 | |
| Sept. 2 |  Partly cloudy | 24° /17° | 0 mm | 5 | |
| Sept. 3 |  Sunny | 24° /16° | 8.6 mm | 4 | |
| Sept. 4 | Sunny | 24° /17° | 4 mm | 6 | |
| Sept. 5 | Sunny | 26° /17° | 11 mm | 7 | |
| Sept. 6 |  Patchy rain possible | 24° /18° | 5.3 mm | 6 | |
| Sept. 7 | Moderate or heavy rain shower | 22° /14° | 5.2 mm | 5 | |
| Sept. 8 | Sunny | 25° /13° | 0 mm | 6 | |
| Sept. 9 | Partly cloudy | 24° /15° | 0.2 mm | 4 | |
| Sept. 10 | Sunny | 25° /17° | 0.4 mm | 4 | |
| Sept. 11 | Partly cloudy | 24° /16° | 0 mm | 6 | |
| Sept. 12 | Sunny | 23° /15° | 0 mm | 6 | |
| Sept. 13 | Sunny | 23° /16° | 0 mm | 6 | |
| Sept. 14 | Sunny | 23° /19° | 0.2 mm | 6 | |
| Sept. 15 | Sunny | 20° /15° | 0 mm | 6.4 | |
| Sept. 16 |  Overcast | 22° /18° | 0 mm | 6.6 | |
| Sept. 17 |  Cloudy | 24° /21° | 0.2 mm | 6 | |
| Sept. 18 | Overcast | 23° /19° | 0.5 mm | 6 | |
| Sept. 19 | Overcast | 22° /19° | 0 mm | 6 | |
| Sept. 20 | Overcast | 25° /20° | 5.8 mm | 5 | |
| Sept. 21 | Overcast | 19° /16° | 0 mm | 5 | |
| Sept. 22 | Patchy rain possible | 18° /15° | 0.8 mm | 4 | |
| Sept. 23 | Light rain shower | 19° /15° | 19.1 mm | 4 | |
| Sept. 24 | Patchy rain possible | 17° /16° | 0.6 mm | 4 | |
| Sept. 25 | Patchy rain possible | 22° /17° | 7.6 mm | 5 | |
| Sept. 26 | Light rain shower | 22° /20° | 10.3 mm | 5 | |
| Sept. 27 | Sunny | 20° /16° | 0.1 mm | 6 | |
| Sept. 28 |  Heavy rain at times | 23° /17° | 7.6 mm | 5 | |
| Sept. 29 | Patchy rain possible | 21° /17° | 1.4 mm | 5 | |
| Sept. 30 | Overcast | 21° /16° | 0 mm | 5 | |
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Long Island in September - FAQ
What are the expected maximum and minimum temperatures in Long Island during September?
How much rainfall should be expected in Long Island during September?
What are the typical wind conditions in Long Island during September?
September rainfall patterns in Long Island
UV exposure in Long Island during September
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