September weather forecast
New Haven, CT

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The greeny New Haven Green in Connecticut, with the rest of the city and a far away dramatic landscape
The greeny New Haven Green in Connecticut, with the rest of the city and a far away dramatic landscape

Weather in September

September weather in New Haven brings a sense of transformation, triggering the advent of the autumnal breeze. Though it follows August's cue of warm days, the fall season paints the city with hues of cranberry red, pumpkin orange, and gilded gold. The temperature starts dropping at month-end, marking an end to the hot summer days. It's a perfect month for exploring the city, witnessing the transition of trees, gardens, and parks embracing the autumn colors.

Temperature

In New Haven, entering September brings a subtle temperature decrement, reducing from August's warm 79.7°F (26.5°C) to an agreeable 72.5°F (22.5°C). New Haven, in September, experiences an average temperature of 60.3°F (15.7°C) at night.

Humidity

The average relative humidity in September is 75%.

Rainfall

The month with the least rainfall in New Haven is September, when the rain falls for 13.4 days and typically collects 2.24" (57mm) of precipitation.

Snowfall

May through October are months without snowfall in New Haven.

Ocean temperature

In New Haven, the average seawater temperature in September is 68.7°F (20.4°C).
Note: The majority of people find swimming in 68.7°F (20.4°C) unenjoyable. As the water temperature decreases from 69.8°F (21°C) to 59°F (15°C), breathing becomes more challenging to control.

Daylight

In September, the average length of the day in New Haven is 12h and 28min.
On the first day of September in New Haven, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:34 pm EDT.

Sunshine

The average sunshine in September is 8.9h.

UV index

In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: In September, a daily UV index of 4 turns into the following recommendations:
Put precautions into practice - Guidance to elude sunburn is provided. Minimize direct exposure to the Sun during midday when its radiation is at its peak. During bright days, sunglasses that offer UVA and UVB defense are recommended.
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Frequently asked questions

What is the average September temperature in New Haven?

In New Haven, 72.5°F (22.5°C) is the average high-temperature and 60.3°F (15.7°C) is the average low-temperature during September.

What is the average humidity in September in New Haven?

The average relative humidity in September in New Haven, Connecticut, is 75%.

What is the driest month in New Haven?

September is the month with the least rainfall in New Haven, Connecticut. Rain falls for 13.4 days and accumulates 2.24" (57mm) of precipitation.

How many days does it rain in September in New Haven?

In New Haven, in September, during 13.4 rainfall days, 2.24" (57mm) of precipitation is typically accumulated.

When it does not snow in New Haven?

In New Haven, snow does not fall in May through October.

What is the ocean temperature in September in New Haven?

In New Haven, Connecticut, in September, the average water temperature is 68.7°F (20.4°C). Swimming in 68.7°F (20.4°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

How many hours of daylight does New Haven have in September?

In September, the average day length in New Haven, Connecticut, is 12h and 28min.

When are sunrise and sunset in September in New Haven?

In September, on the first day of the month, sunrise is at 6:18 am and sunset at 7:24 pm. On the last day of the month, in New Haven, sunrise is at 6:48 am and sunset at 6:34 pm EDT.

How many hours of sunshine does New Haven have in September?

The average sunshine duration in September in New Haven is 8.9h.

What is the UV index intensity in September in New Haven?

In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium health risk from exposure to Sun's UV rays.
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
New Haven, CT

Average temperature in September - New Haven, CT
  • Average high temperature in September: 72.5°F

The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is January (35.1°F).

  • Average low temperature in September: 60.3°F

The month with the highest average low temperature is July (67.6°F).
The coldest month (with the lowest average low temperature) is January (25.5°F).

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Average pressure in September
New Haven, CT

Average pressure in September - New Haven, CT
  • 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).

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Average wind speed in September
New Haven, CT

Average wind speed in September - New Haven, CT
  • Average wind speed in September: 7.7mph

The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.8mph).

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Average humidity in September
New Haven, CT

Average humidity in September - New Haven, CT
  • Average humidity in September: 75%

The months with the highest relative humidity are February, May and June (76%).
The months with the lowest relative humidity are April and November (72%).

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Average rainfall in September
New Haven, CT

Average rainfall in September - New Haven, CT
  • Average rainfall in September: 2.24"

The wettest month (with the highest rainfall) is December (3.86").
The driest month (with the least rainfall) is September (2.24").

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Average rainfall days in September
New Haven, CT

Average rainfall days in September - New Haven, CT
  • Average rainfall days in September: 13.4 days

The month with the highest number of rainy days is July (18 days).
The month with the least rainy days is January (9.4 days).

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Average snowfall in September
New Haven, CT

Average snowfall in September - New Haven, CT
  • Average snowfall in September: 0"

The month with the highest snowfall is March (2.8").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in September
New Haven, CT

Average snowfall days in September - New Haven, CT
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (7.3 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average sea temperature in September
New Haven, CT

Average sea temperature in September - New Haven, CT
  • Average sea temperature in September: 68.8°F

The best month for swimming (with the highest average sea temperature) is August (73°F).
The coldest month (with the lowest average sea temperature) is February (38.5°F).

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Average daylight in September /
Average sunshine in September
New Haven, CT

Average daylight in September / Average sunshine in September - New Haven, CT
  • 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: 8h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).

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Average sunshine days in September
New Haven, CT

Average sunshine days in September - New Haven, CT
  • Average sunshine days in September: 13.9 days

The month with the most sunshine days is November (17.3 days).
The month with the least sunshine days is August (11.3 days).

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Average UV index in September
New Haven, CT

Average UV index in September - New Haven, CT
  • Average UV index in September: 4

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, November and December (UV index 2).

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Average cloud cover in September
New Haven, CT

Average cloud cover in September - New Haven, CT
  • Average cloud cover in September: 33

The months with the most cloud cover are February and December (Cloud cover 48).
The month with the least cloud cover is August (Cloud cover 29).

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Average visibility in September
New Haven, CT

Average visibility in September - New Haven, CT
  • 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).

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New Haven, Connecticut, USA

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