September weather forecastSaint Clair, PA
September
Weather in September
September, the first month of the autumn in Saint Clair, is still a pleasant month, with an average temperature varying between 73°F (22.8°C) and 53.6°F (12°C).Temperature
September sees a slight reduction in average high-temperature, with a shift from a warm 79°F (26.1°C) in August to a pleasant 73°F (22.8°C). Saint Clair, in September, experiences an average temperature of 53.6°F (12°C) at night.Humidity
In September, the average relative humidity is 80%.Rainfall
September is the month with the least rainfall. Rain falls for 12.7 days and accumulates 2.09" (53mm) of precipitation.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 6:32 am and sunset at 7:36 pm. On the last day of the month, sunrise is at 7:01 am and sunset at 6:48 pm EDT.
Sunshine
In Saint Clair, the average sunshine in September is 8.8h.UV index
In Saint Clair, the average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for the ordinary person.Note: In September, the average maximum UV index of 4 translates into the following recommendations:
Make use of precautions - Suggestions to resist sunburn are communicated. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Experience reduced UV exposure by about half when donning a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Clair, PA
- Average high temperature in September: 73°F
The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (32.5°F).
- Average low temperature in September: 53.6°F
The month with the highest average low temperature is July (61.3°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in September
Saint Clair, PA
- Average pressure in September: 30.06"Hg
The month with the highest atmospheric pressure is November (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed in September
Saint Clair, PA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is March (8.4mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in September
Saint Clair, PA
- Average humidity in September: 80%
The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is April (77%).
Average rainfall in September
Saint Clair, PA
- Average rainfall in September: 2.09"
The wettest month (with the highest rainfall) is May (3.39").
The driest month (with the least rainfall) is September (2.09").
Average rainfall days in September
Saint Clair, PA
- Average rainfall days in September: 12.7 days
The month with the highest number of rainy days is May (18.7 days).
The months with the least rainy days are January and November (10.8 days).
Average snowfall in September
Saint Clair, PA
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.47").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Saint Clair, PA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Saint Clair, PA
- Average daylight in September: 12h and 30min
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 18min).
- Average sunshine in September: 8h and 48min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The months with the least sunshine are January, February and December (Average sunshine: 4h and 24min).
Average sunshine days in September
Saint Clair, PA
- Average sunshine days in September: 14.9 days
The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is May (9.6 days).
Average UV index in September
Saint Clair, PA
- Average UV index in September: 4
The month with the highest UV index is July (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
Saint Clair, PA
- Average cloud cover in September: 38
The months with the most cloud cover are February and December (Cloud cover 53).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in September
Saint Clair, PA
- Average visibility in September: 5mi
The month with the highest visibility is April (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October, November and December (5mi).
