July weather forecastChantilly, VA
July
Weather in July
July is a tropical summer month in Chantilly, Virginia, with an average temperature varying between 67.3°F (19.6°C) and 88.2°F (31.2°C).Temperature
The warmest temperatures occur during July, when averages reach a peak of 88.2°F (31.2°C) and a low of 67.3°F (19.6°C).Heat index
The heat index value during July is appraised at a fiery hot 100.4°F (38°C). Exercise more precautions, heat cramps and heat exhaustion are potential risks. Continuous activity could precipitate heatstroke.Consider that heat index readings are for situations in the shade and light wind. A rise in the heat index by 15 Fahrenheit (8 Celsius) degrees may result from direct sunlight exposure.
Note: The heat index, also known as 'felt air temperature' or 'real feel', is a metric representing the sensation of warmth when air temperature and moisture come together. The influence of weather is personal, differing among a variety of individuals based on differences in body mass, stature, and the level of physical activity. Considering the impact of direct sunlight, it's possible for the heat index to surge by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite 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.
Perspiration, which is the evaporation of sweat, is a primary way the human body manages and dispels excessive warmth. Excessive relative humidity disturbs the body's typical cooling process by reducing evaporation, leading to a decrease in body cooling rate and an increase in the sensation of warmth. Heat-related complications, like dehydration, can manifest if the body's heat gain exceeds its dissipation capacity.
Humidity
July is the least humid month, with an average relative humidity of 71%.Rainfall
In Chantilly, in July, during 16.1 rainfall days, 2.91" (74mm) of precipitation is typically accumulated. Throughout the year, there are 156 rainfall days, and 31.18" (792mm) of precipitation is accumulated.Snowfall
May through October are months without snowfall.Daylight
The average length of the day in July is 14h and 35min.On the first day of July in Chantilly, sunrise is at 5:48 am and sunset at 8:39 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 10.7h 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. A UV Index of 6 to 7 symbolizes a high health risk from exposure to the Sun's UV rays for average individuals.Note: A maximum high daily UV index of 6 during July translates into the following directions:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. Avoid direct Sun exposure and seek shade from 10 a.m. to 4 p.m., the period of highest UV radiation. Remember, however, that not all shade structures offer full protection. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in July
Chantilly, VA
- Average high temperature in July: 88.2°F
The warmest month (with the highest average high temperature) is July (88.2°F).
The month with the lowest average high temperature is January (39.7°F).
- Average low temperature in July: 67.3°F
The month with the highest average low temperature is July (67.3°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure in July
Chantilly, 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
Chantilly, VA
- Average wind speed in July: 4.8mph
The windiest months (with the highest average wind speed) are March and April (7.3mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).
Average humidity in July
Chantilly, 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
Chantilly, VA
- Average rainfall in July: 2.91"
The wettest month (with the highest rainfall) is August (3.74").
The driest month (with the least rainfall) is September (1.89").
Average rainfall days in July
Chantilly, VA
- Average rainfall days in July: 16.1 days
The month with the highest number of rainy days is May (17.5 days).
The month with the least rainy days is November (9.3 days).
Average snowfall in July
Chantilly, VA
- Average snowfall in July: 0"
The month with the highest snowfall is January (3.58").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in July
Chantilly, VA
- Average snowfall days in July: 0 days
The month with the highest number of snowfall days is February (5.3 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
Chantilly, VA
- Average daylight in July: 14h and 36min
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 July: 10h and 42min
The month with the most sunshine is July (Average sunshine: 10h and 42min).
The months with the least sunshine are January, February and December (Average sunshine: 5h and 6min).
Average sunshine days in July
Chantilly, VA
- Average sunshine days in July: 12.1 days
The month with the most sunshine days is November (19.6 days).
The month with the least sunshine days is July (12.1 days).
Average UV index in July
Chantilly, 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
Chantilly, VA
- Average cloud cover in July: 31
The month with the most cloud cover is March (Cloud cover 47).
The month with the least cloud cover is July (Cloud cover 31).
Average visibility in July
Chantilly, VA
- Average visibility in July: 6mi
The months with the highest visibility are February, March, April, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January and May (5mi).
