Temperatures in September
It's cool to moderate in September in Long Island with an average temperature of 16°C. Temperatures this month range from a low of 14°C to a high of 18°C. At night, you can expect temperatures between 8°C and 12°C.
Max and Min Temperatures per Day
This chart shows the daily maximum and minimum temperatures in degrees Celsius for Long Island in September. The red line indicates the max temperatures, and the blue line shows the minimums.
Start of September
The month of September starts in Long Island with mild temperatures, averaging around 18°C during the day and nights close to 12°C. Plenty of days with a chance of precipitation.
Mid-September
By mid-September, the average daytime temperature drops to around 17°C, with nights close to 9°C. The chance of precipitation is high during this period.
End of September
By the end of September, the average daytime temperature in Long Island will be around 15°C, with nights close to 10°C. There’s a significant chance of many days with precipitation.
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Precipitation in September
In September, there is an average of 204 mm of precipitation, spread over 17 days. The wind speed is around 4 Bft, mostly coming from the South.
Across the whole month, the average precipitation chance is 57% per day.
Precipitation Chance
This chart shows the daily precipitation chance (in percentages) in September for Long Island. 0% means it never rained on that day in the past 10 years, and 100% means it rained every day. All values in between represent the average chance of precipitation on that day.
Long Island in September |
London | ||
|---|---|---|---|
 Average Temperature |
16°C | 20°C | |
 High Temp |
18°C | 22°C | |
| Low Temp |
14°C | 17°C | |
 Total Precipitation |
204 mm | 44 mm | |
| Rainy Days |
17 days | 8 days | |
August
UV index
The UV index is a maximum of 5 this month. That's a moderate value on the intensity scale of 1 to 11. Unprotected skin can burn in about 30 minutes.
Is September a good time to visit Long Island?
Looking for sun and warm weather? Then September isn’t the best time to be in Long Island. The temperature is too low this month for a warm stay.
Temperature records for Long Island in September
With 25°C, Long Island hit the highest temperature in the last 10 years in September 2019. The lowest daytime temperature in this month was 11°C in 2015. The extreme night temperatures ranged from a low of 1°C to a high of 15°C.
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Daily Temperature in September in Long Island
This chart shows the average daily temperatures, both day and night, for each day in September in Long Island, measured in degrees Celsius. The red line represents the maximum temperatures, while the blue line shows the minimums. The days of the month are displayed at the bottom of the chart. The data, based on historical observations, gives an overview of the average daily temperatures during this month.
Daily Precipitation in September in Long Island
The chart below shows the average daily precipitation in September for Long Island, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail. The days of the month are shown at the bottom of the chart.
A low average precipitation means that the chance of rain on that day is usually small, while a higher average suggests that rain is more likely. But it’s still an average, so each day can be different. Based on historical weather data for September, you can expect around 17 days of rain in Long Island.
Daily UV Index in September in Long Island
This chart shows the average daily UV index in September in Long Island, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Temperature in September in Long Island Over the Years
This chart shows the average temperature in September in Long Island, measured in degrees Celsius, over the past years.
Total Precipitation in September in Long Island Over the Years
This chart shows the average precipitation in September in Long Island, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail.
Daily climate in September for Long Island
Click on a specific day in September for detailed info on the typical weather on that day in Long Island. Check out the historical temperatures and precipitation over the past 10 years on this day.
Weather experiences in September in Long Island
Have you been to Long Island in September?
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Average Weather in Long Island by Month
Click on a month below to see detailed weather info for Long Island. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.
Or check out the climate of Long Island for all months at once
