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 sea temperature 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
The shift from August to September includes a minor decrease in the average high-temperature, lightly dropping from 82.8°F (28.2°C) to a still moderately hot 76.6°F (24.8°C). In Charlestown, in September, the average low-temperature is a mild 59.9°F (15.5°C).Humidity
In Charlestown, the average relative humidity in September is 78%.Rainfall
In Charlestown, in September, it is raining for 12.8 days, with typically 2.05" (52mm) of accumulated precipitation. Throughout the year, there are 150.3 rainfall days, and 29.25" (743mm) of precipitation is accumulated.Snowfall
April, June through October are months without snowfall.Ocean temperature
In Charlestown, the average seawater temperature in September is 72.1°F (22.3°C).Note: Swimming in 72.1°F (22.3°C) waters may not appeal to those sensitive to cold. Yet, the presence of sunshine, the strength of the wind, and the air temperature can alter this experience. Some might even opt for a wetsuit for added comfort.
Daylight
In September, the average length of the day is 12h and 26min.On the first day of the month, sunrise is at 6:32 am and sunset at 7:34 pm. On the last day of September, in Charlestown, sunrise is at 6:59 am and sunset at 6:47 pm EDT.
Sunshine
The average sunshine in September in Charlestown is 9.1h.UV index
In Charlestown, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium health hazard from unprotected exposure to Sun's UV rays for average individuals.Note: The maximum UV index of 5 during September leads to these instructions:
Adopt protective measures - Suggestions to resist sunburn are offered. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. During bright days, sunglasses that offer UVA and UVB defense are recommended. Heed this! UV intensity is much stronger when reflected off sand and water.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How many days does it rain in September?
When it does not snow?
What is the water temperature in September?
What is the average length of the day in September?
What time are sunrise and sunset in September?
How many hours of sunshine does Charlestown have in September?
What is the UV index intensity in September?
Average temperature in September
Charlestown, MD
- Average high temperature in September: 76.6°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 (37.9°F).
- Average low temperature in September: 59.9°F
The month with the highest average low temperature is July (67.6°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).
Average pressure in September
Charlestown, MD
- Average pressure in September: 30.05"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
Charlestown, MD
- Average wind speed in September: 6mph
The windiest months (with the highest average wind speed) are February and March (8.9mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).
Average humidity in September
Charlestown, MD
- Average humidity in September: 78%
The months with the highest relative humidity are May and June (79%).
The month with the lowest relative humidity is April (74%).
Average rainfall in September
Charlestown, MD
- Average rainfall in September: 2.05"
The wettest month (with the highest rainfall) is August (3.86").
The driest month (with the least rainfall) is January (1.85").
Average rainfall days in September
Charlestown, MD
- Average rainfall days in September: 12.8 days
The month with the highest number of rainy days is May (17.4 days).
The month with the least rainy days is January (7.8 days).
Average snowfall in September
Charlestown, MD
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.24").
The months with the least snowfall are April, June, July, August, September and October (0").
Average snowfall days in September
Charlestown, MD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.4 days).
The months with the least snowfall days are April, June, July, August, September and October (0 days).
Average sea temperature in September
Charlestown, MD
- Average sea temperature in September: 72.1°F
The best month for swimming (with the highest average sea temperature) is August (76.3°F).
The coldest month (with the lowest average sea temperature) is February (40.9°F).
Average daylight in September /
Average sunshine in September
Charlestown, MD
- 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: 9h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is February (Average sunshine: 4h and 54min).
Average sunshine days in September
Charlestown, MD
- Average sunshine days in September: 15.4 days
The month with the most sunshine days is November (20.4 days).
The month with the least sunshine days is July (11.6 days).
Average UV index in September
Charlestown, MD
- Average UV index in September: 5
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Charlestown, MD
- Average cloud cover in September: 36
The months with the most cloud cover are February and March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in September
Charlestown, MD
- Average visibility in September: 5mi
The months with the highest visibility are January, February, March, April, June, July, August, October, November and December (6mi).
The months with the lowest visibility are May and September (5mi).
Charlestown, Maryland, USA
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