September weather forecastDerry, PA
September
Weather in September
The first month of the autumn, September, is still a pleasant month in Derry, Pennsylvania, with an average temperature varying between 52.9°F (11.6°C) and 72.9°F (22.7°C).Temperature
With the arrival of September, Derry notices a mild change in the average high-temperature, sliding from August's moderately hot 79.3°F (26.3°C) to a pleasant 72.9°F (22.7°C). During September nights, Derry witnesses a consistent average temperature of 52.9°F (11.6°C).Humidity
The average relative humidity in September is 79%.Rainfall
In September, the rain falls for 12.4 days. Throughout September, 1.22" (31mm) of precipitation is accumulated. Throughout the year, in Derry, there are 156.2 rainfall days, and 19.45" (494mm) of precipitation is accumulated.Snowfall
June through September are months without snowfall.Daylight
The average length of the day in September is 12h and 27min.On the first day of September, sunrise is at 6:45 am and sunset at 7:48 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 7:00 pm EDT.
Sunshine
In September, the average sunshine is 8.6h.UV index
In September, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for average individuals.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Undertake precautions - Guarding against sun damage is counselled. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. During bright days, sunglasses that offer UVA and UVB defense are recommended.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Derry, PA
- Average high temperature in September: 72.9°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (32.2°F).
- Average low temperature in September: 52.9°F
The month with the highest average low temperature is July (59.5°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in September
Derry, PA
- Average pressure in September: 30.06"Hg
The month with the highest atmospheric pressure is November (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.95"Hg).
Average wind speed in September
Derry, PA
- Average wind speed in September: 5.6mph
The windiest month (with the highest average wind speed) is January (9.2mph).
The calmest month (with the lowest average wind speed) is August (5mph).
Average humidity in September
Derry, PA
- Average humidity in September: 79%
The months with the highest relative humidity are January and February (86%).
The months with the lowest relative humidity are April, July and August (78%).
Average rainfall in September
Derry, PA
- Average rainfall in September: 1.22"
The wettest month (with the highest rainfall) is May (2.32").
The driest month (with the least rainfall) is November (1.02").
Average rainfall days in September
Derry, PA
- Average rainfall days in September: 12.4 days
The month with the highest number of rainy days is May (19.8 days).
The month with the least rainy days is January (7.6 days).
Average snowfall in September
Derry, PA
- Average snowfall in September: 0"
The month with the highest snowfall is January (3.94").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Derry, PA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Derry, PA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 8h and 36min
The months with the most sunshine are July and August (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 0min).
Average sunshine days in September
Derry, PA
- Average sunshine days in September: 13.9 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is May (8.9 days).
Average UV index in September
Derry, PA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in September
Derry, PA
- Average cloud cover in September: 40
The month with the most cloud cover is January (Cloud cover 70).
The month with the least cloud cover is August (Cloud cover 36).
Average visibility in September
Derry, PA
- Average visibility in September: 5mi
The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).
