New Haven
Connecticut, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
New Haven, CT

A scenic shot from above of the greeny New Haven Green in Connecticut, with the rest of the city and a far away dramatic landscape
A scenic shot from above of the greeny New Haven Green in Connecticut, with the rest of the city and a far away dramatic landscape
September, the first month of the autumn, in New Haven, is still a warm month, with average temperature varying between 74.5°F (23.6°C) and 56.1°F (13.4°C).

Temperature

In September, the average high-temperature slightly decreases, from a warm 81°F (27.2°C) in August, to a still moderately hot 74.5°F (23.6°C). The average low-temperature, in New Haven, is 56.1°F (13.4°C).

Rainfall

In New Haven, Connecticut, in September, it is raining for 8 days, with typically 4.4" (111mm) of accumulated precipitation. Throughout the year, in New Haven, there are 119 rainfall days, and 47.1" (1196.6mm) of precipitation is accumulated.

Ocean temperature

In New Haven, the average seawater temperature in September 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).

Daylight

In New Haven, the average length of the day is 12.5h.

Sunshine

In September, the average sunshine is 7h.

UV index

In New Haven, the average daily maximum UV index is 6. A UV Index value of 6 to 7 symbolizes a high threat to health from unsafe exposure to the UV radiation for ordinary individuals.
The average daily UV index of 6 in September transform into the following instructions:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.

What is the temperature in September in New Haven?

In New Haven, in September, the average high-temperature is 74.5°F (23.6°C), and the average low-temperature is 56.1°F (13.4°C).

How much does it rain in New Haven in September?

In September, in New Haven, Connecticut, the rain falls for 8 days. Throughout September, 4.4" (111mm) of precipitation is accumulated.

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).

What is the average length of the day in September in New Haven?

In New Haven, the average length of the day in September is 12.5h.

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

In New Haven, Connecticut, the average sunshine in September is 7h.

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

The average daily maximum UV index in September in New Haven, Connecticut, is 6. A UV Index estimate of 6 to 7 represents a high hazard to health from the exposure to the Sun's UV rays.
Average temperature in September - New Haven, CT
  • Average high temperature in September: 74.4°F

The warmest month (with the highest average high temperature) is July (82.5°F).
The month with the lowest average high temperature is January (37.8°F).

  • Average low temperature in September: 56.1°F

The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (22.2°F).

Average rainfall in September - New Haven, CT
  • Average rainfall in September: 4.4"

Wettest months (with the highest rainfall) are April and September (4.4").
The driest month (with the lowest rainfall) is February (2.9").

Average rainfall days in September - New Haven, CT
  • Average rainfall days in September: 8 days

The month with the highest number of rainy days is December (12 days).
The month with the lowest number of rainy days is October (7 days).

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).

Average daylight in September / Average sunshine in September - New Haven, CT
  • Average daylight in September: 12.5h

The month with the longest days is June (Average daylight: 15.1h).
The month with shortest days is December (Average daylight: 9.2h).

  • Average sunshine in September: 7h

Months with most sunshine are May, June and July (Average sunshine: 9h).
Months with least sunshine are November and December (Average sunshine: 5).

Average UV index in September - New Haven, CT
  • Average UV index in September: 6

Months with the highest UV index are June, July and August (UV index 8).
The month with the lowest UV index is December (UV index 1).