September weather forecastGaithersburg, MD
September
Weather in September
Gaithersburg's September weather represents the gateway to fall, with temperatures declining from the peak summer highs to a range from 59.9°F (15.5°C) to 77.7°F (25.4°C). September sees a fall in both humidity and precipitation levels compared to August. A typical September day will experience warmth with a touch of cool breezes. The weather is nothing short of perfect for enjoying the vibrant fall foliage in local parks.Temperature
A minor decrease in the average high-temperature is observed in Gaithersburg during September, shifting from a warm 84.6°F (29.2°C) in August to a still moderately hot 77.7°F (25.4°C). Gaithersburg observes an average nighttime temperature of 59.9°F (15.5°C) during September.Humidity
In Gaithersburg, the average relative humidity in September is 75%.Rainfall
In Gaithersburg, in September, during 12.9 rainfall days, 1.97" (50mm) of precipitation is typically accumulated. In Gaithersburg, Maryland, during the entire year, the rain falls for 154.8 days and collects up to 29.09" (739mm) of precipitation.Snowfall
June through October are months without snowfall.Daylight
The average length of the day in September is 12h and 26min.On the first day of September in Gaithersburg, sunrise is at 6:38 am and sunset at 7:39 pm. On the last day of the month, sunrise is at 7:04 am and sunset at 6:52 pm EDT.
Sunshine
In Gaithersburg, the average sunshine in September is 9h.UV index
In Gaithersburg, the average daily maximum UV index in September is 5. A UV Index of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: The maximum UV index of 5 during September leads to these instructions:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. 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
Gaithersburg, MD
- Average high temperature in September: 77.7°F
The warmest month (with the highest average high temperature) is July (86.9°F).
The month with the lowest average high temperature is January (38.8°F).
- Average low temperature in September: 59.9°F
The month with the highest average low temperature is July (67.6°F).
The coldest month (with the lowest average low temperature) is January (25.2°F).
Average pressure in September
Gaithersburg, 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 (29.95"Hg).
Average wind speed in September
Gaithersburg, MD
- Average wind speed in September: 5.5mph
The windiest month (with the highest average wind speed) is March (8mph).
The calmest month (with the lowest average wind speed) is August (4.9mph).
Average humidity in September
Gaithersburg, MD
- Average humidity in September: 75%
The months with the highest relative humidity are May, October and December (77%).
The month with the lowest relative humidity is July (72%).
Average rainfall in September
Gaithersburg, MD
- Average rainfall in September: 1.97"
The wettest month (with the highest rainfall) is August (3.82").
The driest month (with the least rainfall) is January (1.73").
Average rainfall days in September
Gaithersburg, MD
- Average rainfall days in September: 12.9 days
The month with the highest number of rainy days is May (17.4 days).
The month with the least rainy days is January (8.7 days).
Average snowfall in September
Gaithersburg, MD
- Average snowfall in September: 0"
The month with the highest snowfall is January (2.76").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in September
Gaithersburg, MD
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is February (5.3 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in September /
Average sunshine in September
Gaithersburg, 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 0min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 6min).
Average sunshine days in September
Gaithersburg, MD
- Average sunshine days in September: 14.9 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (11.5 days).
Average UV index in September
Gaithersburg, 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, February, November and December (UV index 2).
Average cloud cover in September
Gaithersburg, 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 30).
Average visibility in September
Gaithersburg, MD
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, June, July, August, September, October, November and December (6mi).
The month with the lowest visibility is May (5mi).
