September weather forecastSaint Louis, VA
September
Weather in September
September, the first month of the autumn in Saint Louis, is still a warm month, with an average temperature fluctuating between 58.3°F (14.6°C) and 77.4°F (25.2°C).Temperature
September is marked by a subtle drop in average high-temperatures, transitioning from 84.6°F (29.2°C) in August to a still moderately hot 77.4°F (25.2°C). Saint Louis registers a consistent average low-temperature of 58.3°F (14.6°C) during September.Humidity
In September, the average relative humidity is 77%.Rainfall
September is the month with the least rainfall. Rain falls for 13.7 days and accumulates 1.93" (49mm) of precipitation.Snowfall
May through September are months without snowfall.Daylight
In September, the average length of the day is 12h and 26min.On the first day of September, sunrise is at 6:40 am and sunset at 7:41 pm. On the last day of the month, sunrise is at 7:06 am and sunset at 6:54 pm EDT.
Sunshine
In September, the average sunshine is 8.9h.UV index
In September, the average daily maximum UV index is 4. A UV Index of 3 to 5 symbolizes a medium health hazard from exposure to the Sun's UV radiation for ordinary individuals.Note: The UV index of 4 in September translates into these instructions:
Be vigilant - Suggestions to stave off sun damage are provided. For health reasons, it's advisable to reduce direct sun exposure during peak hours around midday. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Saint Louis, VA
- Average high temperature in September: 77.4°F
The warmest month (with the highest average high temperature) is July (86.5°F).
The month with the lowest average high temperature is January (38.7°F).
- Average low temperature in September: 58.3°F
The month with the highest average low temperature is July (65.5°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).
Average pressure in September
Saint Louis, VA
- 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 (29.95"Hg).
Average wind speed in September
Saint Louis, VA
- Average wind speed in September: 5mph
The windiest month (with the highest average wind speed) is March (7.3mph).
The calmest month (with the lowest average wind speed) is August (4.4mph).
Average humidity in September
Saint Louis, VA
- Average humidity in September: 77%
The months with the highest relative humidity are October and December (78%).
The month with the lowest relative humidity is July (73%).
Average rainfall in September
Saint Louis, VA
- Average rainfall in September: 1.93"
The wettest months (with the highest rainfall) are May and August (3.35").
The driest month (with the least rainfall) is September (1.93").
Average rainfall days in September
Saint Louis, VA
- Average rainfall days in September: 13.7 days
The month with the highest number of rainy days is May (17.3 days).
The month with the least rainy days is January (10.1 days).
Average snowfall in September
Saint Louis, VA
- Average snowfall in September: 0"
The month with the highest snowfall is January (4.17").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in September
Saint Louis, VA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (6.8 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
Saint Louis, VA
- 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: 8h and 54min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The months with the least sunshine are January and December (Average sunshine: 5h and 6min).
Average sunshine days in September
Saint Louis, VA
- Average sunshine days in September: 14.7 days
The month with the most sunshine days is November (19.3 days).
The month with the least sunshine days is May (11.1 days).
Average UV index in September
Saint Louis, VA
- 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
Saint Louis, VA
- Average cloud cover in September: 36
The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 30).
Average visibility in September
Saint Louis, VA
- Average visibility in September: 5mi
The months with the highest visibility are February, March, April, June, July, August and November (6mi).
The months with the lowest visibility are January, May, September, October and December (5mi).
