July weather forecastFairfax, VA
July
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
In Fairfax, temperatures reach their average annual highs in July, measuring 88°F (31.1°C) and a minimum average of 68.4°F (20.2°C).Heat index
For July, the heat index is computed to be a torrid 100.4°F (38°C). Greater safety measures are needed, risk of heat exhaustion and heat cramps is high. Continuous activity might trigger heatstroke.Remember that heat index calculations are made for conditions in the shade with light wind. Direct sunlight might cause an increase of up to 15 Fahrenheit (8 Celsius) degrees in the heat index.
Note: The heat index, also known as 'feels like' or 'real feel', determines the feeling of heat when you account for the relative humidity. Elements such as metabolic variations, pregnancy, and physical exertion can shape one's weather perception. 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 extremely vital to babies and toddlers. Kids are usually more vulnerable than adults, given their lesser sweating ability. Along with their larger skin surface relative to their small stature and the excess heat due to their activity, their risk is amplified.
As a reaction to high temperatures, the human body begins to perspire, using the evaporation of sweat to lower its temperature. Higher relative humidity impedes evaporation, thus reducing heat dispersion from the body, culminating in a sensation of overheating. Accumulating more heat than the body can dissipate leads to an uptick in body temperature, with potential heat stress consequences.
Humidity
With an average relative humidity of 71%, July is the least humid month.Rainfall
In July, the rain falls for 17 days. Throughout July, 3.03" (77mm) of precipitation is accumulated. In Fairfax, during the entire year, the rain falls for 162 days and collects up to 31.65" (804mm) of precipitation.Snowfall
May through October are months without snowfall.Daylight
In Fairfax, the average length of the day in July is 14h and 34min.On the first day of July, 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
The months with the highest UV index are May through August, with an average maximum UV index of 6. A UV Index value of 6 to 7 symbolizes a high threat to health from exposure to the Sun's UV rays for the average person.Note: The daily high UV index of 6 in July translates into this advice:
Sustain precautions and conform to sun safety norms. Preventing sunburn is necessary. Avoid direct Sun exposure and stay in the shade between 10 a.m. and 4 p.m., a time when UV radiation is most intense, noting that not all shade structures offer full protection. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
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).
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).
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).
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%).
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").
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).
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").
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).
Average daylight in July /
Average sunshine in July
Fairfax, VA
- Average daylight in July: 14h and 36min
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 48min
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).
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).
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).
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).
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).
