September weather forecast
Manassas, VA

Weather in September

September, the first month of the autumn, in Manassas, is also a moderately hot month, with average temperature ranging between max 79°F (26.1°C) and min 59.7°F (15.4°C).

Temperature

In September, the average high-temperature slightly decreases, from 85.8°F (29.9°C) in August, to a still moderately hot 79°F (26.1°C). The average low-temperature, in September, is 59.7°F (15.4°C).

Humidity

The average relative humidity in Manassas is 76%.

Rainfall

September is the month with the least rainfall. Rain falls for 12.7 days and accumulates 1.93" (49mm) of precipitation.

Snowfall

In Manassas snow does not fall in May through October.

Daylight

The average length of the day in Manassas is 12.4h.

Sunshine

In Manassas, the average sunshine is 8.7h.

UV index

The average daily maximum UV index in Manassas is 5. A UV Index value of 3 to 5 symbolizes a moderate health risk from the exposure to the Sun's UV rays for the average person.
Note: In September, the average maximum UV index of 5 translate into the following recommendations:
Take precautions - Protection against sunburn is recommended. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes.
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FAQ

What is the average humidity in September in Manassas?

In September, the average relative humidity in Manassas, Virginia, is 76%.

What is the driest month in Manassas?

September is the month with the least rainfall. Rain falls for 12.7 days and accumulates 1.93" (49mm) of precipitation.

How much does it rain in Manassas in September?

In September, in Manassas, the rain falls for 12.7 days. Throughout September, 1.93" (49mm) of precipitation is accumulated.

When it does not snow in Manassas?

In Manassas, Virginia, snow does not fall in May through October.

What is the average length of the day in September in Manassas?

The average length of the day in September in Manassas is 12.4h.

How many hours of sunshine does Manassas have in September?

In Manassas, Virginia, the average sunshine in September is 8.7h.

What is the UV index intensity in September in Manassas?

In September, the average daily maximum UV index is 5. A UV Index of 3 to 5 symbolizes a moderate health threat from the exposure to the Sun's UV rays.

Average temperature in September
Manassas, VA

Average temperature in September - Manassas, VA
  • Average high temperature in September: 26.1°C

The warmest month (with the highest average high temperature) is July (31.3°C).
The month with the lowest average high temperature is January (4.8°C).

  • Average low temperature in September: 15.4°C

The month with the highest average low temperature is July (19.5°C).
The coldest month (with the lowest average low temperature) is January (-3.1°C).

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Average pressure in September
Manassas, VA

Average pressure in September - Manassas, VA
  • Average pressure in September: 1017.7mbar

The month with the highest atmospheric pressure is November (1020.7mbar).
The month with the lowest atmospheric pressure is June (1014.2mbar).

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Average wind speed in September
Manassas, VA

Average wind speed in September - Manassas, VA
  • Average wind speed in September: 8.2km/h

The windiest months (with the highest average wind speed) are March and April (11.2km/h).
The calmest month (with the lowest average wind speed) is August (7.4km/h).

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Average humidity in September
Manassas, VA

Average humidity in September - Manassas, VA
  • Average humidity in September: 76%

The month with the highest relative humidity is December (78%).
The month with the lowest relative humidity is July (72%).

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Average rainfall in September
Manassas, VA

Average rainfall in September - Manassas, VA
  • Average rainfall in September: 49mm

The wettest month (with the highest rainfall) is August (87mm).
The driest month (with the least rainfall) is September (49mm).

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Average rainfall days in September
Manassas, VA

Average rainfall days in September - Manassas, VA
  • Average rainfall days in September: 12.7 days

The month with the highest number of rainy days is May (17.4 days).
The month with the least rainy days is November (9.3 days).

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Average snowfall in September
Manassas, VA

Average snowfall in September - Manassas, VA
  • Average snowfall in September: 0mm

The month with the highest snowfall is January (94mm).
The months with the least snowfall are May, June, July, August, September and October (0mm).

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Average snowfall days in September
Manassas, VA

Average snowfall days in September - Manassas, VA
  • Average snowfall days in September: 0 days

The month with the highest number of snowfall days is February (5.2 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Manassas, VA

Average daylight in September / Average sunshine in September - Manassas, VA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.8h).
The month with the shortest days is December (Average daylight: 9.5h).

  • Average sunshine in September: 8.7h

The month with the most sunshine is July (Average sunshine: 10.7h).
The months with the least sunshine are January, February and December (Average sunshine: 5.2).

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Average sunshine days in September
Manassas, VA

Average sunshine days in September - Manassas, VA
  • Average sunshine days in September: 15.9 days

The month with the most sunshine days is November (19.8 days).
The month with the least sunshine days is May (11.7 days).

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Average UV index in September
Manassas, VA

Average UV index in September - Manassas, VA
  • 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).

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Average cloud cover in September
Manassas, VA

Average cloud cover in September - Manassas, VA
  • Average cloud cover in September: 38

The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 31).

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Average visibility in September
Manassas, VA

Average visibility in September - Manassas, VA
  • Average visibility in September: 8km

The months with the highest visibility are January, February, March, April, June, July, August and November (9km).
The months with the lowest visibility are May, September, October and December (8km).

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