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
A mild shift in the average high-temperature occurs in September, reducing from 82°F (27.8°C) in August to a still moderately hot 75°F (23.9°C). Mercersburg experiences an average low-temperature reading of 55.4°F (13°C) throughout September.Humidity
The average relative humidity in September is 78%.Rainfall
The month with the least rainfall is September, when the rain falls for 14 days and typically collects 2.05" (52mm) of precipitation.Snowfall
May through September are months without snowfall in Mercersburg.Daylight
In Mercersburg, the average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:42 pm. On the last day of September, sunrise is at 7:07 am and sunset at 6:55 pm EDT.
Sunshine
In September, the average sunshine is 8.6h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for the average person.Note: The UV index of 4 during September translates into the following guidance:
Ensure safety - Sun damage prevention is strongly urged. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Experience reduced UV exposure by about half when donning a wide-brim hat.
Frequently asked questions
What are the temperatures in Mercersburg in September?
What is the average humidity in September in Mercersburg?
What is the driest month in Mercersburg?
How much does it rain in Mercersburg in September?
When it does not snow in Mercersburg?
Does it snow in Mercersburg in September?
How many hours of daylight does Mercersburg have in September?
When are sunrise and sunset in September in Mercersburg?
How many hours of sunshine does Mercersburg have in September?
What is the UV index intensity in September in Mercersburg?
Average temperature in September
Mercersburg, PA
- Average high temperature in September: 75°F
The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is January (35.2°F).
- Average low temperature in September: 55.4°F
The month with the highest average low temperature is July (62.6°F).
The coldest month (with the lowest average low temperature) is January (22.1°F).
Average pressure in September
Mercersburg, 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
Mercersburg, PA
- Average wind speed in September: 4.8mph
The windiest month (with the highest average wind speed) is January (7.5mph).
The calmest month (with the lowest average wind speed) is August (4.3mph).
Average humidity in September
Mercersburg, PA
- Average humidity in September: 78%
The months with the highest relative humidity are February, May, October and December (79%).
The months with the lowest relative humidity are April and July (75%).
Average rainfall in September
Mercersburg, PA
- Average rainfall in September: 2.05"
The wettest month (with the highest rainfall) is May (3.19").
The driest month (with the least rainfall) is September (2.05").
Average rainfall days in September
Mercersburg, PA
- Average rainfall days in September: 14 days
The month with the highest number of rainy days is May (18.8 days).
The month with the least rainy days is November (9.9 days).
Average snowfall in September
Mercersburg, PA
- Average snowfall in September: 0"
The month with the highest snowfall is January (5.2").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Mercersburg, PA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (9.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Mercersburg, PA
- Average daylight in September: 12h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in September: 8h and 4min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in September
Mercersburg, PA
- Average sunshine days in September: 14.2 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is May (10.3 days).
Average UV index in September
Mercersburg, 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
Mercersburg, PA
- Average cloud cover in September: 39
The months with the most cloud cover are January, February and December (Cloud cover 50).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in September
Mercersburg, PA
- Average visibility in September: 5mi
The months with the highest visibility are April, June, July and November (6mi).
The months with the lowest visibility are January, February, March, May, August, September, October and December (5mi).
Mercersburg, Pennsylvania, USA
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