September weather forecast
Derby, CT

Weather in September

September, the first month of the autumn in Derby, is still a pleasant month, with temperature in the range of an average low of 59.4°F (15.2°C) and an average high of 73°F (22.8°C).

Temperature

In Derby, the average high-temperature in September slightly decreases from a warm 80.2°F (26.8°C) in August to an agreeable 73°F (22.8°C). In September, the average low-temperature is 59.4°F (15.2°C).

Humidity

The average relative humidity in September is 76%.

Rainfall

The month with the least rainfall in Derby is September, when the rain falls for 13.1 days and typically collects 2.24" (57mm) of precipitation.

Snowfall

In Derby, snow does not fall in May through October.

Daylight

The average length of the day in September in Derby is 12h and 28min.
On the first day of the month, sunrise is at 6:18 am and sunset at 7:26 pm. On the last day of September, sunrise is at 6:47 am and sunset at 6:36 pm EDT.

Sunshine

In Derby, the average sunshine in September is 8.9h.

UV index

The average daily maximum UV index in September in Derby is 4. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for average individuals.
Note: The average daily UV index of 4 in September transform into the following instructions:
Take precautions - Protection against skin and eye damage is obliged. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. 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.
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FAQ

What is the temperature in September in Derby?

The average high-temperature, in September, is 73°F (22.8°C), while the average low-temperature is 59.4°F (15.2°C). in July, the average heat index (a.k.a. 'feels like', 'felt air temperature'), which calculates the temperature value influenced by the moisture in the air, is appraised at 87.8°F (31°C).

What is the average humidity in September in Derby?

The average relative humidity in September in Derby is 76%.

What is the driest month in Derby?

September is the month with the least rainfall. Rain falls for 13.1 days and accumulates 2.24" (57mm) of precipitation.

How many days does it rain in September in Derby?

In September, in Derby, the rain falls for 13.1 days. Throughout September, 2.24" (57mm) of precipitation is accumulated.

When it does not snow in Derby?

In Derby, snow does not fall in May through October.

What is the average length of the day in September in Derby?

In September, the average day length in Derby is 12h and 28min.

When are sunrise and sunset in September in Derby?

In September, on the first day of the month, sunrise is at 6:18 am and sunset at 7:26 pm. On the last day of the month, in Derby, Connecticut, sunrise is at 6:47 am and sunset at 6:36 pm EDT.

How long on average sun shines in September in Derby?

In Derby, Connecticut, the average sunshine duration in September is 8.9h.

How high is the UV index in September in Derby?

In Derby, Connecticut, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium health risk from unprotected exposure to UV radiation.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Derby, CT

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).

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Average pressure in September
Derby, CT

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).

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Average wind speed in September
Derby, CT

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).

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Average humidity in September
Derby, CT

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%).

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Average rainfall in September
Derby, CT

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").

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Average rainfall days in September
Derby, CT

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).

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Average snowfall in September
Derby, CT

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").

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Average snowfall days in September
Derby, CT

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).

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

Average daylight in September / Average sunshine in September - Derby, CT
  • Average daylight in September: 12h and 28min

The month with the longest days is June (Average daylight: 15h and 7min).
The month with the shortest days is December (Average daylight: 9h and 15min).

  • 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).

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Average sunshine days in September
Derby, CT

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).

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Average UV index in September
Derby, CT

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).

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Average cloud cover in September
Derby, CT

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).

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Average visibility in September
Derby, CT

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).

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