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 is marked by a subtle drop in average high-temperatures, transitioning from 79.9°F (26.6°C) in August to a still warm 73.8°F (23.2°C). Throughout September, Cornwall's nights cool down to an average of 55.4°F (13°C).Humidity
In Cornwall, 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. Throughout the year, there are 137.4 rainfall days, and 16.26" (413mm) of precipitation is accumulated.Snowfall
In Cornwall, 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 6:33 am and sunset at 7:36 pm. On the last day of September, in Cornwall, 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 Cornwall, 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 ordinary person.Note: The UV index of 4 in September translates into these instructions:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage.
Published by: Weather U.S. | 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 in Cornwall?
When it does not snow in Cornwall?
Does it snow in September?
How many hours of daylight does Cornwall have in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Cornwall have in September?
How high is the UV index in September?
Average temperature in September
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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
Cornwall, 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).
Cornwall, Pennsylvania, USA
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