July weather forecast
Fairfax, VA

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Weather in July

July in Fairfax, Virginia, stands out as the hottest month of the year with a soaring average high temperature of 88°F (31.1°C). It seems by now, the summer sun has taken full control, the rain is heavy but intermittent, and thunderstorm activity is frequently observed. In spite of the highly warm temperatures, the month experiences the least wind velocity throughout the year. As the city moves from July into August, it prepares for a gradual reduction in temperatures.

Temperature

July, noted for its average high-temperature of 88°F (31.1°C) and an average low-temperature of 68.4°F (20.2°C), is considered the warmest month.

Heat index

In July, the average heat index is appraised at a torrid 100.4°F (38°C). Take greater precautions, heat exhaustion and heat cramps may be expected. Heatstroke could result from lengthy activity.
When considering the heat index, it's pivotal to note it is for shade and mild wind conditions. The heat index may experience an enhancement of 15 Fahrenheit (8 Celsius) degrees under direct sunlight.
Note: The heat index, also known as 'felt air temperature' or 'feels like', evaluates the perceived heat by adding the effect of moisture in the air. Factors encompassing physical activity, clothing, and metabolic differences have a role in shaping the individual's impression of temperature. Realize that direct exposure to sunlight can augment the felt heat, leading to a potential increase in the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are highly important for children. Kids are usually in more danger than grown-ups as they tend to sweat less. Plus, their bigger skin surface in relation to their small frames and increased heat generation due to their activity level make them more susceptible.
The body's innate mechanism to counteract overheating is through perspiration, as it leverages the cooling effects of sweat evaporation. When the relative humidity is high, the evaporation rate is reduced. The warmth is removed from the body at a lower rate, causing the body to retain more heat than it would in dry air. As the body gains more heat than it can dissipate, there's a risk of increasing temperatures and resultant overheating.

Humidity

With an average relative humidity of 71%, July is the least humid month in Fairfax, Virginia.

Rainfall

In Fairfax, in July, it is raining for 17 days, with typically 3.03" (77mm) of accumulated precipitation. Throughout the year, in Fairfax, there are 162 rainfall days, and 31.65" (804mm) of precipitation is accumulated.

Snowfall

May through October are months without snowfall.

Daylight

The average length of the day in July is 14h and 34min.
On the first day of July in Fairfax, sunrise is at 5:48 am and sunset at 8:38 pm. On the last day of the month, sunrise is at 6:10 am and sunset at 8:21 pm EDT.

Sunshine

With an average of 10.8h of sunshine, July has the most sunshine of the year.

UV index

May through August, with an average maximum UV index of 6, are months with the highest UV index in Fairfax. A UV Index of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for the ordinary person.
Note: The daily high UV index of 6 during July translates into the following recommendations:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. Avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is most intense, and remember that not all shade structures provide full protection. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
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Frequently asked questions

What is the hottest time of year in Fairfax?

Temperature readings in Fairfax, Virginia, reach their annual highs in July, averaging 88°F (31.1°C) and a minimum average of 68.4°F (20.2°C).

How hot is it in Fairfax in July?

An average high-temperature, in July, in Fairfax, is 88°F (31.1°C) and the average low-temperature is 68.4°F (20.2°C). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which takes the relative humidity and factors it into the air temperature reading, in July is appraised at 100.4°F (38°C).

What is the least humid month in Fairfax?

With an average relative humidity of 71%, July is the least humid month in Fairfax, Virginia.

What is the average humidity in July in Fairfax?

The average relative humidity in July in Fairfax is 71%.

How much does it rain in Fairfax in July?

In Fairfax, during July, the rain falls for 17 days and regularly aggregates up to 3.03" (77mm) of precipitation.

When it does not snow in Fairfax?

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

What is the average length of the day in July in Fairfax?

The average day length in July in Fairfax, Virginia, is 14h and 34min.

When are sunrise and sunset in July in Fairfax?

On the first day of July in Fairfax, Virginia, sunrise is at 5:48 am and sunset at 8:38 pm. On the last day of the month, sunrise is at 6:10 am and sunset at 8:21 pm EDT.

What month has the most sunshine in Fairfax?

The month with the most sunshine is July, with an average of 10.8h of sunshine.

How many hours of sunshine does Fairfax have in July?

The average sunshine duration in July in Fairfax, Virginia, is 10.8h.

What is the month with the highest UV index in Fairfax?

May through August, with an average maximum UV index of 6, are months with the highest UV index.

What is the UV index reading in July in Fairfax?

In July, the average daily maximum UV index in Fairfax is 6. A UV Index of 6 to 7 symbolizes a high health vulnerability from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in July
Fairfax, VA

Average temperature in July - Fairfax, VA
  • Average high temperature in July: 88°F

The warmest month (with the highest average high temperature) is July (88°F).
The month with the lowest average high temperature is January (40.5°F).

  • Average low temperature in July: 68.4°F

The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (26.4°F).

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Average pressure in July
Fairfax, VA

Average pressure in July - Fairfax, VA
  • Average pressure in July: 29.97"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).

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Average wind speed in July
Fairfax, VA

Average wind speed in July - Fairfax, VA
  • Average wind speed in July: 4.8mph

The windiest month (with the highest average wind speed) is March (7.4mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).

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Average humidity in July
Fairfax, VA

Average humidity in July - Fairfax, VA
  • Average humidity in July: 71%

The months with the highest relative humidity are October and December (77%).
The month with the lowest relative humidity is July (71%).

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Average rainfall in July
Fairfax, VA

Average rainfall in July - Fairfax, VA
  • Average rainfall in July: 3.03"

The wettest month (with the highest rainfall) is August (3.78").
The driest month (with the least rainfall) is September (2.01").

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Average rainfall days in July
Fairfax, VA

Average rainfall days in July - Fairfax, VA
  • Average rainfall days in July: 17 days

The months with the highest number of rainy days are May and August (17.3 days).
The month with the least rainy days is November (9.1 days).

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Average snowfall in July
Fairfax, VA

Average snowfall in July - Fairfax, VA
  • Average snowfall in July: 0"

The month with the highest snowfall is January (3.54").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in July
Fairfax, VA

Average snowfall days in July - Fairfax, VA
  • Average snowfall days in July: 0 days

The month with the highest number of snowfall days is January (5.6 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 July /
Average sunshine in July
Fairfax, VA

Average daylight in July / Average sunshine in July - Fairfax, VA
  • Average daylight in July: 14h and 4min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in July: 10h and 5min

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 12min).

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Average sunshine days in July
Fairfax, VA

Average sunshine days in July - Fairfax, VA
  • Average sunshine days in July: 11.3 days

The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (11.3 days).

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Average UV index in July
Fairfax, VA

Average UV index in July - Fairfax, VA
  • Average UV index in July: 6

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 July
Fairfax, VA

Average cloud cover in July - Fairfax, VA
  • Average cloud cover in July: 30

The month with the most cloud cover is March (Cloud cover 46).
The month with the least cloud cover is July (Cloud cover 30).

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Average visibility in July
Fairfax, VA

Average visibility in July - Fairfax, VA
  • Average visibility in July: 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).

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Fairfax, Virginia, USA

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