August Weather in Fairfax, United States

Last updated: June 24, 2025

In August, the average temperature in Fairfax, United States is a pleasant 21°C (71°F), with temperatures ranging from a cool 9°C (49°F) to a warm 35°C (95°F). Visitors should prepare for some rain, as 124 mm (4.9 in) of precipitation is expected over 11 days. Additionally, the average humidity hovers around 81%, contributing to a generally moist atmosphere.

August Temperature in Fairfax

In August in Fairfax, the average temperature is 21°C (71°F). Maximums can reach 35°C (95°F) and minimums can be as low as 9°C (49°F). This makes it an ideal time for travelers to enjoy a variety of outdoor activities while being prepared for both warm days and cooler evenings.

August Weather in Fairfax: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in Fairfax, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Fairfax, August typically has an average temperature of 21°C (71°F), with highs reaching up to 35°C (95°F) and lows dropping to around 9°C (49°F).

Data source: Temperature data for Fairfax generated using information from the Copernicus Climate Change Service.

August Precipitation in Fairfax

In Fairfax in August, the precipitation amount is 124 mm (4.9 in) over the course of 11 days.

August Precipitation Trends in Fairfax

The chart displays monthly precipitation patterns in Fairfax, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Fairfax, August typically receives around 124 mm (4.9 inches) of precipitation spread over approximately 11 days.

Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

August Humidity in Fairfax

In Fairfax in August, humidity is 81%. With an average temperature of 21°C (71°F), this humidity feels like a warm, enveloping blanket that makes traveling feel both refreshing and slightly heavy, often leading to a sticky sensation that can quickly deplete your energy.

August Average Humidity in Fairfax

This chart illustrates the average monthly humidity levels in Fairfax, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, average humidity in Fairfax is approximately 81%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in Fairfax

In Fairfax in August, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Fairfax.

Maximum UV Index Levels in Fairfax for August

The chart shows the monthly maximum UV Index (UVI) for Fairfax in August, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In August, the maximum UV index in Fairfax typically reaches 9, which falls under the very high exposure category.

Data source: Fairfax August UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How August Weather in Fairfax Compares to Other Months

Weather in Fairfax varies notably across the year, with each month offering distinct climate conditions. This page compares August’s weather to other months in Fairfax, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Fairfax, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-9°C (16°F)	26 mm (1.0 inches)	87%	moderate
February Weather	-9°C (16°F)	27 mm (1.1 inches)	90%	moderate
March Weather	0°C (33°F)	62 mm (2.5 inches)	85%	moderate
April Weather	6°C (43°F)	80 mm (3.1 inches)	84%	very high
May Weather	15°C (60°F)	124 mm (4.9 inches)	78%	very high
June Weather	22°C (72°F)	106 mm (4.2 inches)	80%	very high
July Weather	23°C (74°F)	123 mm (4.8 inches)	81%	very high
August Weather	21°C (71°F)	124 mm (4.9 inches)	81%	very high
September Weather	18°C (65°F)	118 mm (4.6 inches)	81%	very high
October Weather	9°C (48°F)	97 mm (3.8 inches)	84%	moderate
November Weather	1°C (34°F)	30 mm (1.2 inches)	88%	moderate
December Weather	-4°C (24°F)	40 mm (1.6 inches)	84%	low