September weather forecastMount Rainier, MD
September
Weather in September
September's weather in Mount Rainier introduces the first hints of autumn, characterized by a decreasing number of daylight hours and lower temperatures. The obvious shift from the hot August months marks itself with a drop in the maximum temperature down to 78.1°F (25.6°C). As the end of the summer season is acknowledged, the cloud coverage starts to increase, creating a scenic view of the city. Looking forward to October, the weather becomes cooler, and the amount of rainfall shows a distinctive increase.Temperature
With September's onset, the weather reveals a slight temperature decrease, transitioning from a warm 85.1°F (29.5°C) in August to a still moderately hot 78.1°F (25.6°C). Mount Rainier's temperature drops to an average low of 62.2°F (16.8°C) during the nights of September.Humidity
The average relative humidity in September is 74%.Rainfall
In Mount Rainier, in September, during 12.3 rainfall days, 2.09" (53mm) of precipitation is typically accumulated. Throughout the year, there are 157.9 rainfall days, and 31.14" (791mm) of precipitation is accumulated.Snowfall
In Mount Rainier, snow does not fall in May through November.Daylight
The average length of the day in September is 12h and 26min.On the first day of September, sunrise is at 6:37 am and sunset at 7:37 pm. On the last day of the month, sunrise is at 7:03 am and sunset at 6:51 pm EDT.
Sunshine
In September, the average sunshine in Mount Rainier is 9.1h.UV index
In Mount Rainier, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV rays for average individuals.Note: In September, an average UV index of 5 transforms into the following instructions:
Undertake protective steps - Recommendations to avoid sunburn are issued. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Opt for tightly woven and loose clothing to enhance protection from the Sun.
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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
Mount Rainier, 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).
