September weather forecastMount Gretna, PA
September
Weather in September
The first month of the autumn, September, is also a moderately hot month in Mount Gretna, Pennsylvania, with an average temperature fluctuating between 55.4°F (13°C) and 73.8°F (23.2°C).Temperature
In Mount Gretna, entering September brings a subtle temperature decrement, reducing from August's warm 79.9°F (26.6°C) to a still moderately hot 73.8°F (23.2°C). Nighttime temperatures consistently average a refreshing 55.4°F (13°C) during September.Humidity
In Mount Gretna, the average relative humidity in September is 80%.Rainfall
In September, the rain falls for 10.5 days. Throughout September, 1.02" (26mm) of precipitation is accumulated. In Mount Gretna, during the entire year, the rain falls for 137.4 days and collects up to 16.26" (413mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
In Mount Gretna, the average length of the day in September is 12h and 27min.On the first day of the month, sunrise is at 6:34 am and sunset at 7:37 pm. On the last day of September, sunrise is at 7:01 am and sunset at 6:49 pm EDT.
Sunshine
The average sunshine in September is 8.8h.UV index
In September, the average daily maximum UV index is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unsafe exposure to UV radiation for the average person.Note: In September, a daily UV index of 4 turns into the following recommendations:
Preventative actions are necessary - Suggestions to safeguard against sun damage are in order. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mount Gretna, PA
- Average high temperature in September: 73.8°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.8°F).
- Average low temperature in September: 55.4°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).
Average pressure in September
Mount Gretna, 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
Mount Gretna, PA
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is March (8.8mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).
Average humidity in September
Mount Gretna, PA
- Average humidity in September: 80%
The months with the highest relative humidity are February, May and October (81%).
The month with the lowest relative humidity is April (76%).
Average rainfall in September
Mount Gretna, PA
- Average rainfall in September: 1.02"
The wettest month (with the highest rainfall) is August (2.13").
The driest month (with the least rainfall) is February (0.94").
Average rainfall days in September
Mount Gretna, PA
- Average rainfall days in September: 10.5 days
The month with the highest number of rainy days is May (15.9 days).
The month with the least rainy days is January (6.7 days).
Average snowfall in September
Mount Gretna, PA
- Average snowfall in September: 0"
The month with the highest snowfall is January (1.97").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Mount Gretna, PA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (5.2 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Mount Gretna, 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 48min
The month with the most sunshine is July (Average sunshine: 10h and 24min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).
Average sunshine days in September
Mount Gretna, PA
- Average sunshine days in September: 16.5 days
The month with the most sunshine days is January (20.3 days).
The month with the least sunshine days is May (11.5 days).
Average UV index in September
Mount Gretna, PA
- Average UV index in September: 4
The months with the highest UV index are May, June and 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
Mount Gretna, PA
- Average cloud cover in September: 38
The months with the most cloud cover are February and December (Cloud cover 51).
The month with the least cloud cover is July (Cloud cover 32).
Average visibility in September
Mount Gretna, PA
- Average visibility in September: 5mi
The months with the highest visibility are January, February, March, April, June, July, November and December (6mi).
The months with the lowest visibility are May, August, September and October (5mi).
