September weather forecastCos Cob, CT
September
Weather in September
Comes September, the transition from summer to autumn brings about a change in the weather in Cos Cob. The temperatures are cooler and days shorter than August. The high and low temperatures range from 73.4°F (23°C) to 61.7°F (16.5°C), making days comfortable for outdoor activities involving the fantastic fall foliage. Despite the decrease in daylight hours to 12.5, the visibility remains clear. Observe how the vibrancy of September's weather in Cos Cob provides a cozy contrast from the hot summer months.Temperature
As September begins in Cos Cob, there is a minor decrease in the average high-temperature, softly falling from 80.6°F (27°C) in August to a still warm 73.4°F (23°C). During September, the nighttime temperature averages of 61.7°F (16.5°C).Humidity
In Cos Cob, the average relative humidity in September is 74%.Rainfall
In Cos Cob, during September, the rain falls for 13.5 days and regularly aggregates up to 2.72" (69mm) of precipitation. In Cos Cob, 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 Cos Cob, in September, the average water temperature is 68.9°F (20.5°C).Note: Swimming is not an enjoyable activity for the majority when the water is at 68.9°F (20.5°C). The difficulty of controlling breathing increases as the temperature dips from 69.8°F (21°C) to 59°F (15°C).
Daylight
In Cos Cob, the average length of the day in September is 12h and 28min.On the first day of September, sunrise is at 6:21 am and sunset at 7:26 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 6:37 pm EDT.
Sunshine
In Cos Cob, the average sunshine in September is 8.8h.UV index
In Cos Cob, Connecticut, the average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unsafe exposure to UV radiation for the ordinary person.Note: A maximum UV index of 4 in September translates into the following recommendations:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Enhance your sun protection with tightly woven, yet airy clothing.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Cos Cob, 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).
Average pressure in September
Cos Cob, CT
- Average pressure in September: 30.05"Hg
The month with the highest atmospheric pressure is November (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in September
Cos Cob, 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).
Average humidity in September
Cos Cob, CT
- Average humidity in September: 74%
The months with the highest relative humidity are February, May and December (75%).
The month with the lowest relative humidity is August (71%).
Average rainfall in September
Cos Cob, 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").
Average rainfall days in September
Cos Cob, 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).
Average snowfall in September
Cos Cob, CT
- Average snowfall in September: 0"
The month with the highest snowfall is February (2.52").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Cos Cob, CT
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average sea temperature in September
Cos Cob, 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).
Average daylight in September /
Average sunshine in September
Cos Cob, CT
- Average daylight in September: 12h and 30min
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 48min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in September
Cos Cob, 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).
Average UV index in September
Cos Cob, 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).
Average cloud cover in September
Cos Cob, 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).
Average visibility in September
Cos Cob, 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).
