September weather forecastTwin Knolls, MD
September
Weather in September
The first month of the autumn, September, is still a warm month in Twin Knolls, Maryland, with an average temperature fluctuating between 75.9°F (24.4°C) and 58.8°F (14.9°C).Temperature
With the onset of September, Twin Knolls's average high-temperature slightly adjusts, moderately receding from August's warm 82.4°F (28°C) to a still moderately hot 75.9°F (24.4°C). An average nighttime temperature of 58.8°F (14.9°C) is noted during the month of September.Humidity
In September, the average relative humidity is 78%.Rainfall
In Twin Knolls, in September, it is raining for 13.7 days, with typically 2.24" (57mm) of accumulated precipitation. In Twin Knolls, during the entire year, the rain falls for 158.9 days and collects up to 31.38" (797mm) of precipitation.Snowfall
In Twin Knolls, snow does not fall in May through September.Daylight
The average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:36 am and sunset at 7:38 pm. On the last day of September, in Twin Knolls, sunrise is at 7:03 am and sunset at 6:51 pm EDT.
Sunshine
The average sunshine in September is 8.9h.UV index
The average daily maximum UV index in September is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for the ordinary person.Note: A daily high UV index of 4 in September leads to these guidelines:
Undertake precautions - Guarding against sun damage is counselled. Sun exposure should be minimized, especially during midday, to avoid harmful UV radiation. Shield yourself from the harmful effects of UV radiation with sun-protective attire, a hat, and quality sunglasses.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Twin Knolls, MD
- Average high temperature in September: 75.9°F
The warmest month (with the highest average high temperature) is July (84.2°F).
The month with the lowest average high temperature is January (37.4°F).
- Average low temperature in September: 58.8°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).
Average pressure in September
Twin Knolls, MD
- 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 (29.94"Hg).
Average wind speed in September
Twin Knolls, MD
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is March (8.9mph).
The calmest months (with the lowest average wind speed) are July and August (5.3mph).
Average humidity in September
Twin Knolls, MD
- Average humidity in September: 78%
The month with the highest relative humidity is May (80%).
The months with the lowest relative humidity are January, March, April, July and November (75%).
Average rainfall in September
Twin Knolls, MD
- Average rainfall in September: 2.24"
The wettest month (with the highest rainfall) is August (3.86").
The driest month (with the least rainfall) is February (1.89").
Average rainfall days in September
Twin Knolls, MD
- Average rainfall days in September: 13.7 days
The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is January (8.3 days).
Average snowfall in September
Twin Knolls, MD
- Average snowfall in September: 0"
The month with the highest snowfall is March (3.46").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Twin Knolls, MD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.6 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
Twin Knolls, MD
- Average daylight in September: 12h and 24min
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 54min
The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in September
Twin Knolls, MD
- Average sunshine days in September: 15.4 days
The month with the most sunshine days is November (18.9 days).
The month with the least sunshine days is May (11.2 days).
Average UV index in September
Twin Knolls, MD
- Average UV index in September: 4
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
Twin Knolls, MD
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 48).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in September
Twin Knolls, 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).
