September weather forecastDerby, CT
September
Weather in September
September in Derby gifts the city with a gradual transition from summer heat to mild autumnal weather. The changing seasons bring picturesque foliage to the city, contributing to the scenic beauty. Random spurts of rain continue to fall, maintaining the city's moisture levels as the days start to shorten. October promises a further fall in temperatures, giving way to cooler days and nights.Temperature
The onset of September in Derby entails a subtle temperature shift, as the average high-temperature eases from a warm 80.2°F (26.8°C) in August to an agreeable 73°F (22.8°C). September in Derby generally records an average low-temperature of 59.4°F (15.2°C).Humidity
In Derby, the average relative humidity in September is 76%.Rainfall
September is the month with the least rainfall. Rain falls for 13.1 days and accumulates 2.24" (57mm) of precipitation.Snowfall
May through October are months without snowfall in Derby.Daylight
In September, the average length of the day in Derby, Connecticut, is 12h and 28min.On the first day of the month, sunrise is at 6:19 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 September, the average sunshine in Derby, Connecticut, is 8.9h.UV index
The average daily maximum UV index in September in Derby is 4. A UV Index estimate of 3 to 5 represents a moderate health risk from exposure to the Sun's UV rays for ordinary individuals.Note: A typical high UV index of 4 in September suggests the following recommendations:
Exercise prevention - Protecting skin and eyes from harm is required. Limiting sun exposure during midday hours helps in reducing the harmful effects of UV radiation. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Derby, CT
- Average high temperature in September: 73°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (34.7°F).
- Average low temperature in September: 59.4°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (24.6°F).
Average pressure in September
Derby, 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).
Average wind speed in September
Derby, CT
- Average wind speed in September: 7mph
The windiest month (with the highest average wind speed) is January (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).
Average humidity in September
Derby, CT
- Average humidity in September: 76%
The month with the highest relative humidity is February (77%).
The month with the lowest relative humidity is April (72%).
Average rainfall in September
Derby, CT
- Average rainfall in September: 2.24"
The wettest month (with the highest rainfall) is December (4.06").
The driest month (with the least rainfall) is September (2.24").
Average rainfall days in September
Derby, CT
- Average rainfall days in September: 13.1 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).
Average snowfall in September
Derby, CT
- Average snowfall in September: 0"
The month with the highest snowfall is February (3.23").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Derby, CT
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (7.8 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Derby, 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 54min
The months with the most sunshine are July and August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in September
Derby, CT
- Average sunshine days in September: 14.4 days
The month with the most sunshine days is November (17.5 days).
The month with the least sunshine days is June (10.3 days).
Average UV index in September
Derby, 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
Derby, CT
- Average cloud cover in September: 34
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 30).
Average visibility in September
Derby, 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).
