September weather forecastRiverdale Park, MD
September
Weather in September
September, the first month of the autumn in Riverdale Park, is also a moderately hot month, with temperature in the range of an average low of 62.2°F (16.8°C) and an average high of 78.1°F (25.6°C).Temperature
The onset of September entails a subtle temperature shift, as the average high-temperature eases from a warm 85.1°F (29.5°C) in August to a still moderately hot 78.1°F (25.6°C). During September, the average low-temperature is an enjoyable 62.2°F (16.8°C).Humidity
In Riverdale Park, Maryland, the average relative humidity in September is 74%.Rainfall
In Riverdale Park, during September, the rain falls for 12.3 days and regularly aggregates up to 2.09" (53mm) of precipitation. Throughout the year, there are 157.9 rainfall days, and 31.14" (791mm) of precipitation is accumulated.Snowfall
In Riverdale Park, Maryland, snow does not fall in May through November.Daylight
The average length of the day in September in Riverdale Park 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
In September, the average sunshine is 9.1h.UV index
In Riverdale Park, the average daily maximum UV index in September is 5. A UV Index estimate of 3 to 5 represents a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: In September, the maximum UV index of 5 translates into these guidelines:
Put precautions into practice - Guidance to elude sunburn is provided. The mid-day Sun emits the most powerful UV radiation, so seek shade and minimize exposure. To cut down UV radiation exposure by about half, sport a wide-brim hat.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Riverdale Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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 Park, 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).
