September weather forecast and climate
Greenwich, CT

The straight road of North Street cutting through the green leafy suburbs of the scenic Greenwich City in Connecticut
The straight road of North Street cutting through the green leafy suburbs of the scenic Greenwich City in Connecticut

Weather in September

September, the first month of the autumn, in Greenwich, is still a warm month, with average temperature fluctuating between 61.7°F (16.5°C) and 73.4°F (23°C).

Temperature

In September, the average high-temperature marginally drops, from 80.6°F (27°C) in August, to a still moderately hot 73.4°F (23°C). In Greenwich, the average low-temperature is 61.7°F (16.5°C).

Humidity

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

Rainfall

In Greenwich, it is raining for 13.5 days, with typically 2.72" (69mm) of accumulated precipitation. In Greenwich, during the entire year, the rain falls for 165.6 days and collects up to 37.64" (956mm) of precipitation.

Snowfall

May through October are months without snowfall.

Ocean temperature

In Greenwich, the average seawater temperature is 68.9°F (20.5°C).
Note: For swimming, a surface water temperature of 68.9°F (20.5°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

Daylight

In Greenwich, the average length of the day in September is 12.4h.

Sunshine

In Greenwich, the average sunshine is 8.8h.

UV index

In September, the average daily maximum UV index in Greenwich is 4. A UV Index of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to the Sun's UV rays for the average person.
Note: The average daily UV index of 4 in September transform into the following instructions:
Take precautions - Protection against sun damage is advised. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
[Resources]

FAQ

What is the average humidity in September in Greenwich?

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

How much does it rain in Greenwich in September?

In Greenwich, during September, the rain falls for 13.5 days and regularly aggregates up to 2.72" (69mm) of precipitation.

When it does not snow in Greenwich?

In Greenwich, Connecticut, snow does not fall in May through October.

How cold is the water in September in Greenwich?

In Greenwich, in September, the average water temperature is 68.9°F (20.5°C). For swimming, a surface water temperature of 68.9°F (20.5°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

How many hours of daylight does Greenwich have in September?

In September, the average length of the day in Greenwich is 12.4h.

How many hours of sunshine does Greenwich have in September?

In September, the average sunshine in Greenwich is 8.8h.

What is the UV index intensity in September in Greenwich?

In Greenwich, Connecticut, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health risk from unsafe exposure to the Sun's UV rays.

Average temperature in September
Greenwich, CT

Average temperature in September - Greenwich, CT
  • Average high temperature in September: 73.4°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (35.8°F).

  • Average low temperature in September: 61.7°F

The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).

[Resources]

Average pressure in September
Greenwich, CT

Average pressure in September - Greenwich, CT
  • Average pressure in September: 30.05"

The month with the highest atmospheric pressure is November (30.1").
The month with the lowest atmospheric pressure is June (29.93").

[Resources]

Average wind speed in September
Greenwich, CT

Average wind speed in September - Greenwich, CT
  • Average wind speed in September: 7.5mph

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is July (6.5mph).

[Resources]

Average humidity in September
Greenwich, CT

Average humidity in September - Greenwich, CT
  • Average humidity in September: 74%

Months with the highest relative humidity are February, May and December (75%).
The month with the lowest relative humidity is August (71%).

[Resources]

Average rainfall in September
Greenwich, CT

Average rainfall in September - Greenwich, CT
  • Average rainfall in September: 2.72"

The wettest month (with the highest rainfall) is July (4.13").
The driest months (with the least rainfall) are January and February (2.4").

[Resources]

Average rainfall days in September
Greenwich, CT

Average rainfall days in September - Greenwich, CT
  • Average rainfall days in September: 13.5 days

The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is January (7.9 days).

[Resources]

Average snowfall in September
Greenwich, CT

Average snowfall in September - Greenwich, CT
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.52").
Months with the least snowfall are May, June, July, August, September and October (0").

[Resources]

Average snowfall days in September
Greenwich, CT

Average snowfall days in September - Greenwich, CT
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is January (7.2 days).
Months with the least snowfall days are June, July, August, September and October (0 days).

[Resources]

Average sea temperature in September
Greenwich, CT

Average sea temperature in September - Greenwich, CT
  • Average sea temperature in September: 68.9°F

The best month for swimming (with the highest average sea temperature) is August (73.1°F).
The coldest month (with the lowest average sea temperature) is February (39.5°F).

[Resources]

Average daylight in September /
Average sunshine in September
Greenwich, CT

Average daylight in September / Average sunshine in September - Greenwich, CT
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 15.1h).
The month with the shortest days is December (Average daylight: 9.3h).

  • Average sunshine in September: 8.8h

The month with the most sunshine is July (Average sunshine: 10.5h).
The month with the least sunshine is February (Average sunshine: 4.7h).

[Resources]

Average sunshine days in September
Greenwich, CT

Average sunshine days in September - Greenwich, CT
  • Average sunshine days in September: 14.3 days

The month with the most sunshine days is November (17.8 days).
The month with the least sunshine days is June (10.7 days).

[Resources]

Average UV index in September
Greenwich, CT

Average UV index in September - Greenwich, CT
  • Average UV index in September: 4

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

[Resources]

Average cloud cover in September
Greenwich, CT

Average cloud cover in September - Greenwich, CT
  • Average cloud cover in September: 35

The month with the most cloud cover is December (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 31).

[Resources]

Average visibility in September
Greenwich, CT

Average visibility in September - Greenwich, CT
  • Average visibility in September: 6mi

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

[Resources]

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location
* you will be automatically redirected to the weather forecast for your location