September weather forecast
Ronkonkoma, NY

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Weather in September

September, the first month of the autumn in Ronkonkoma, is still a pleasant month, with an average temperature fluctuating between 65.3°F (18.5°C) and 72.1°F (22.3°C).

Temperature

Ronkonkoma's September weather features a light decline in high-temperatures, reducing from a moderately hot 78.1°F (25.6°C) in August to an agreeable 72.1°F (22.3°C). In Ronkonkoma, the nightly September temperatures experience a slight descent from daily highs to an average low of 65.3°F (18.5°C).

Humidity

In Ronkonkoma, the average relative humidity in September is 74%.

Rainfall

In Ronkonkoma, in September, during 12.8 rainfall days, 2.48" (63mm) of precipitation is typically accumulated. Throughout the year, there are 155.3 rainfall days, and 34.84" (885mm) of precipitation is accumulated.

Snowfall

April, June through September and November are months without snowfall.

Daylight

In Ronkonkoma, the average length of the day in September is 12h and 27min.
On the first day of the month, sunrise is at 6:20 am and sunset at 7:24 pm. On the last day of September, sunrise is at 6:48 am and sunset at 6:35 pm EDT.

Sunshine

In Ronkonkoma, New York, the average sunshine in September is 9.2h.

UV index

In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for ordinary individuals.
Note: In September, the maximum UV index of 5 suggests this advice:
Act with care - The need to guard against sun damage is communicated. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades.
Updated: Aug 12, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the average September temperature?

An average high-temperature, in September, in Ronkonkoma, is 72.1°F (22.3°C) and the average low-temperature is 65.3°F (18.5°C).

What is the average humidity in September?

The average relative humidity in September is 74%.

How much does it rain in September?

In Ronkonkoma, New York, in September, during 12.8 rainfall days, 2.48" (63mm) of precipitation is typically accumulated.

When it does not snow?

April, June through September and November are months without snowfall.

Does it snow in September?

In Ronkonkoma, in September, it doesn't snow. In October, it regularly snows.

How many hours of daylight does Ronkonkoma have in September?

The average day length in September is 12h and 27min.

When is the sunrise / sunset in September?

On the first day of September, sunrise is at 6:20 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:35 pm EDT.

How long on average sun shines in September?

In September, the average sunshine duration is 9.2h.

How high is the UV index in September?

The average daily maximum UV index in September is 5. A UV Index value of 3 to 5 symbolizes a moderate health threat from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Ronkonkoma, NY

Average temperature in September - Ronkonkoma, NY
  • Average high temperature in September: 72.1°F

The warmest month (with the highest average high temperature) is August (78.1°F).
The month with the lowest average high temperature is January (37.9°F).

  • Average low temperature in September: 65.3°F

The month with the highest average low temperature is August (71.8°F).
The coldest month (with the lowest average low temperature) is January (30.2°F).

Average pressure in September
Ronkonkoma, NY

Average pressure in September - Ronkonkoma, NY
  • Average pressure in September: 30.05"Hg

The month with the highest atmospheric pressure is November (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in September
Ronkonkoma, NY

Average wind speed in September - Ronkonkoma, NY
  • Average wind speed in September: 10.4mph

The windiest month (with the highest average wind speed) is January (13.8mph).
The calmest months (with the lowest average wind speed) are July and August (9mph).

Average humidity in September
Ronkonkoma, NY

Average humidity in September - Ronkonkoma, NY
  • Average humidity in September: 74%

The months with the highest relative humidity are May and June (78%).
The month with the lowest relative humidity is November (71%).

Average rainfall in September
Ronkonkoma, NY

Average rainfall in September - Ronkonkoma, NY
  • Average rainfall in September: 2.48"

The wettest month (with the highest rainfall) is December (3.74").
The driest month (with the least rainfall) is January (2.17").

Average rainfall days in September
Ronkonkoma, NY

Average rainfall days in September - Ronkonkoma, NY
  • Average rainfall days in September: 12.8 days

The month with the highest number of rainy days is July (17.7 days).
The month with the least rainy days is January (8.3 days).

Average snowfall in September
Ronkonkoma, NY

Average snowfall in September - Ronkonkoma, NY
  • Average snowfall in September: 0"

The month with the highest snowfall is March (2.13").
The months with the least snowfall are April, June, July, August, September and November (0").

Average snowfall days in September
Ronkonkoma, NY

Average snowfall days in September - Ronkonkoma, NY
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (4.6 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in September /
Average sunshine in September
Ronkonkoma, NY

Average daylight in September / Average sunshine in September - Ronkonkoma, NY
  • Average daylight in September: 12h and 3min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in September: 9h and 1min

The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).

Average sunshine days in September
Ronkonkoma, NY

Average sunshine days in September - Ronkonkoma, NY
  • Average sunshine days in September: 15.1 days

The month with the most sunshine days is November (18.8 days).
The month with the least sunshine days is July (11.3 days).

Average UV index in September
Ronkonkoma, NY

Average UV index in September - Ronkonkoma, NY
  • Average UV index in September: 5

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March and December (UV index 2).

Average cloud cover in September
Ronkonkoma, NY

Average cloud cover in September - Ronkonkoma, NY
  • Average cloud cover in September: 31

The month with the most cloud cover is December (Cloud cover 48).
The month with the least cloud cover is August (Cloud cover 27).

Average visibility in September
Ronkonkoma, NY

Average visibility in September - Ronkonkoma, NY
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

Ronkonkoma, New York, USA

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