Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
September brings a minor shift in the average high-temperature, adjusting from a moderately hot 79.9°F (26.6°C) in August to a still warm 73.8°F (23.2°C). September nights in Mount Gretna are marked by an average low-temperature of 55.4°F (13°C).Humidity
In September, the average relative humidity is 80%.Rainfall
In Mount Gretna, during September, the rain falls for 10.5 days and regularly aggregates up to 1.02" (26mm) of precipitation. Throughout the year, there are 137.4 rainfall days, and 16.26" (413mm) of precipitation is accumulated.Snowfall
In Mount Gretna, snow does not fall in June through September.Daylight
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
In September, the average sunshine is 8.8h.UV index
In September, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: The daily high UV index of 4 during September translates into the following recommendations:
Be mindful. Individuals with a lighter skin tone may suffer burns in less than 30 minutes. The midday Sun can be dangerous due to its intense radiation; always find shade and reduce exposure. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are September temperatures?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Mount Gretna have in September?
When is the sunrise / sunset in September?
How many hours of sunshine does Mount Gretna have in September?
How high is the UV index in September?
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 2min
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 5min
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).
Mount Gretna, Pennsylvania, USA
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