September weather forecastRiverdale Heights, MD
September
Weather in September
September, the first month of the autumn in Riverdale Heights, is also a moderately hot month, with an average temperature fluctuating between 62.2°F (16.8°C) and 78.1°F (25.6°C).Temperature
The onset of September entails a subtle temperature shift, as the average high-temperature eases from a moderately hot 85.1°F (29.5°C) in August to a still warm 78.1°F (25.6°C). Riverdale Heights observes an average low-temperature of 62.2°F (16.8°C) during September nights.Humidity
The average relative humidity in September is 74%.Rainfall
In Riverdale Heights, in September, it is raining for 12.3 days, with typically 2.09" (53mm) of accumulated precipitation. In Riverdale Heights, during the entire year, the rain falls for 157.9 days and collects up to 31.14" (791mm) of precipitation.Snowfall
May through November are months without snowfall.Daylight
The average length of the day in September is 12h and 26min.On the first day of the month, sunrise is at 6:37 am and sunset at 7:37 pm. On the last day of September, sunrise is at 7:03 am and sunset at 6:51 pm EDT.
Sunshine
The average sunshine in September is 9.1h.UV index
In September, the average daily maximum UV index is 5. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV radiation for the average person.Note: The maximum daily UV index of 5 in September interprets into the following recommendations:
Undertake protective steps - Obligation to safeguard skin and eyes from harm is in place. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. 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
Average temperature in September
Riverdale Heights, MD
- Average high temperature in September: 78.1°F
The warmest month (with the highest average high temperature) is July (87.4°F).
The month with the lowest average high temperature is January (39.9°F).
- Average low temperature in September: 62.2°F
The month with the highest average low temperature is July (70°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).
Average pressure in September
Riverdale Heights, MD
- Average pressure in September: 30.05"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
Riverdale Heights, MD
- Average wind speed in September: 6.1mph
The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).
Average humidity in September
Riverdale Heights, MD
- Average humidity in September: 74%
The months with the highest relative humidity are May, October and December (76%).
The months with the lowest relative humidity are April and July (71%).
Average rainfall in September
Riverdale Heights, MD
- Average rainfall in September: 2.09"
The wettest month (with the highest rainfall) is August (3.58").
The driest month (with the least rainfall) is January (2.01").
Average rainfall days in September
Riverdale Heights, MD
- Average rainfall days in September: 12.3 days
The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is November (9 days).
Average snowfall in September
Riverdale Heights, MD
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.6").
The months with the least snowfall are May, June, July, August, September, October and November (0").
Average snowfall days in September
Riverdale Heights, MD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (4.1 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Riverdale Heights, 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 30min).
- Average sunshine in September: 9h and 6min
The month with the most sunshine is July (Average sunshine: 10h and 54min).
The month with the least sunshine is February (Average sunshine: 5h and 0min).
Average sunshine days in September
Riverdale Heights, MD
- Average sunshine days in September: 15.6 days
The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is May (11.8 days).
Average UV index in September
Riverdale Heights, 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 and December (UV index 2).
Average cloud cover in September
Riverdale Heights, MD
- Average cloud cover in September: 36
The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 29).
Average visibility in September
Riverdale Heights, MD
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
