Climate and monthly weather forecastFairfax, VA
Climate and monthly weather forecast
The climate of Fairfax
Fairfax, Virginia, located in the United States of America, experiences a Humid subtropical climate condition, often identified as Cfa by the Köppen climate classification. This specifically denotes that the region does not have a dry season and faces a rather wet, humid climate throughout the year.Over the 12-month calendar, the region experiences a broad range of temperatures fluctuating from a low 26.4°F (-3.1°C) in the colder months to 88°F (31.1°C) during the peak of summer. Humidity levels stay relatively steady all year, varying only slightly between 71-77%. Precipitation in the form of rainfall is consistent, ranging from 2.01" (51mm) to 3.78" (96mm) per month, occurring on an average of 9.1 to 17.3 days per month.
In winters, the region experiences a considerable amount of snowfall from 0.08" (2mm) to 3.54" (90mm), primarily concentrated during the days between December and February. The daylight duration varies from a minimum of 9.5 hours a day in December to a maximum of 14.9 hours a day in June.
The strength of the ultraviolet rays, indicated by the UV Index, reaches a maximum of 6 during the summer months and decreases to 2 during the colder months. The mean visibility remains fairly constant at 6 miles throughout the year. Wind speeds vary between 4.7mph (7.6km/h) to 7.4mph (11.9km/h), with maximum gusts reaching up to 11.2mph (18km/h).
The best time to visit Fairfax
The optimal time frame for visiting Fairfax would likely stands in the warmer months of the year, around May to September. During this period, average temperatures remain comfortable from 65.1°F (18.4°C) to 88°F (31.1°C), while daylight hours are the longest, peaking at 14.9 hours during June. Yet, it should be noted that ultraviolet radiation from the sun reaches its highest levels during these months, so adequate precautions should be taken to protect against sunburn.The worst time to visit Fairfax
The period from December till February can be considered as not ideal for a visit to Fairfax. During this time, average temperatures are at their lowest, dropping to 26.4°F (-3.1°C) and averaging only 9.5 hours of daylight. This season also records highest snowfalls and reduced visibility.Spring weather in Fairfax
Spring in Fairfax is typically mild with average temperatures ranging from 36.9°F (2.7°C) to 65.1°F (18.4°C). Rainfall sees a slight increase during this period, reaching up to 2.44" (62mm) in March and 2.8" (71mm) in April. Daylight hours also start to increase offering more sun exposure, ideal for outdoor activities.Summer weather in Fairfax
During the summer months of June, July and August, Fairfax experiences its highest temperatures ranging from 82.9°F (28.3°C) to 88°F (31.1°C) along with a steep increase in humidity levels. Despite these high temperatures, the summer season also sees the longest daylight hours, providing ample time to explore the region.Autumn weather in Fairfax
Autumn witnesses a comfortable decrease in temperature from 78.4°F (25.8°C) in September to a cool 54.5°F (12.5°C) in November. Humidity levels and rainfall see a gradual decline during this period, making it a comfortable time for outdoor activities.Winter weather in Fairfax
Winter, starting from December, brings significantly cooler temperatures, reaching as low as 26.4°F (-3.1°C) in January. This season also sees the least daylight hours and highest snowfall rates, making it the most challenging time for outdoor activities. As the year wraps up, Fairfax's winter climate encapsulates the truly diverse weather conditions present through the 12-month cycle.Weather in January
Beginning the calendar year in Fairfax, Virginia, the weather in January tends to have lower temperatures, compared to the impending warmth in succeeding months. January’s average high thermostat reading is 40.5°F (4.7°C). Being the first month of the year, the city has a moderate amount of rainfall with the bulk coming in from 10.4 days on average. Weather in January »Weather in February
Fairfax, Virginia, experiences a gradual increase in average temperatures moving from January into February. This climatic shift is noticeable, but the chills of winter can still be felt throughout the month. Indeed, the mean low temperature for February records at 29.1°F (-1.6°C). Weather in February »Weather in March
March marks the transition period in Fairfax, Virginia, from the lingering winter to the welcoming spring, with weather patterns reflecting both seasons. Interestingly, the median sunlight duration reaches 12 hours during March. The shifts in climatic variables suggest a gradual uptick in temperatures, a stable phase for relative humidity, and an increase in rainfall. Weather in March »Weather in April
Moving deeper into spring, April in Fairfax, Virginia indicates a continuance of climbing temperatures from March, essentially bidding winter completely goodbye. The warmer conditions in April result in an average high temperature of 65.1°F (18.4°C). Weather in April »Weather in May
May in Fairfax, Virginia, marks the ingress of the summer season. The temperature highs move further upwards, posting warmer days and the snowfall from winter months is non-existent. May emerges as the rainiest month with an average precipitation of 3.11in. Weather in May »Weather in June
As the mid-year mark approaches, June arrives with the full bloom of summer in Fairfax, Virginia. The rising temperatures are reciprocated with a peak UV index rating at 6, encouraging residents to take precautionary measures. Despite temperatures continuing to trend upwards, pre-dawn conditions remain cooler indicating wide diurnal temperature variations. Weather in June »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. Weather in July »Weather in August
August in Fairfax, Virginia, signals the start of a subtle decline in temperatures while still maintaining the warmth associated with the summer months. It's still a peak summer month but with slightly less intensity compared to July. Weather in August »Weather in September
September announces the onset of fall in Fairfax, Virginia. The transition from August is apparent with diminishing daylight hours, a drop in temperature highs, and a concurrent decrease in the UV index. The month experiences balanced weather conditions in terms of rainfall, sunlight, and relative humidity. Weather in September »Weather in October
October in Fairfax, Virginia, brings a stronger sense of fall as temperatures further drop and daylight hours decrease. However, the decrease in temperature is gradual since October isn't typically associated with major cold snaps. Weather in October »Weather in November
November in Fairfax, Virginia, ushers in significant changes in weather, characterized by fewer daylight hours, lower temperatures, and decreased sunlight duration. The decrease in temperatures is felt even more with November registering an average low of 38.5°F (3.6°C). Weather in November »Weather in December
As the final month of the year, December takes over in Fairfax, Virginia, with solid winter weather patterns including low temperatures, reduced daylight hours, and increased snowfall. While the month isn’t the coldest, it can offer a significant amount of snowfall with an average of 1.73in. Weather in December »Updated: Jun 15, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
In Fairfax, January is the month with the lowest recorded average temperatures, measuring a high of 40.5°F (4.7°C) and a low of 26.4°F (-3.1°C).
Throughout the year, there are 162 rainfall days, and 31.65" (804mm) of precipitation is accumulated.
Months with snowfall are January through April, November and December.
January is the month with the most snowfall. Snow falls for 5.6 days and accumulates 3.54" (90mm) of snow.
Throughout the year, there are 18 snowfall days, and 11.18" (284mm) of snow is accumulated.
The months with the least sunshine in Fairfax, Virginia, are January, February and December, with an average of 5.2h of sunshine.
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index.
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from EST to EDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from EDT to EST.
May through October are months without snowfall.
The months with the highest UV index are May through August, with an average maximum UV index of 6.
The month with the longest days is June, with an average of 14h and 48min of daylight.
July stands out as Fairfax's warmest month, with an average high-temperature of 88°F (31.1°C) and a low-temperature of 68.4°F (20.2°C).
With an average relative humidity of 71%, July is the least humid month.
The month with the most sunshine is July, with an average of 10.8h of sunshine.
The month with the most rainfall is August, when the rain falls for 17.3 days and typically aggregates up to 3.78" (96mm) of precipitation.
September is the month with the least rainfall. Rain falls for 13.1 days and accumulates 2.01" (51mm) of precipitation.
October and December, with an average relative humidity of 77%, are most humid months.
With an average of 9h and 30min of daylight, December has the shortest days of the year.
Average temperature
Fairfax, VA
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).
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
Fairfax, VA
- Average pressure in January:
30.11"Hg - Average pressure in February:
30.08"Hg - Average pressure in March:
30.08"Hg - Average pressure in April:
29.99"Hg - Average pressure in May:
30.01"Hg - Average pressure in June:
29.95"Hg
- Average pressure in July:
29.97"Hg - Average pressure in August:
29.99"Hg - Average pressure in September:
30.05"Hg - Average pressure in October:
30.04"Hg - Average pressure in November:
30.14"Hg - Average pressure in December:
30.11"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
Fairfax, VA
- Average wind speed in January:
7.1mph - Average wind speed in February:
7.1mph - Average wind speed in March:
7.4mph - Average wind speed in April:
7.3mph - Average wind speed in May:
6.1mph - Average wind speed in June:
5.5mph
- Average wind speed in July:
4.8mph - Average wind speed in August:
4.7mph - Average wind speed in September:
5.3mph - Average wind speed in October:
6.2mph - Average wind speed in November:
6.5mph - Average wind speed in December:
6.5mph
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
Fairfax, VA
The months with the highest relative humidity are October and December (77%).
The month with the lowest relative humidity is July (71%).
Average rainfall
Fairfax, VA
- Average rainfall in January:
2.09" - Average rainfall in February:
2.09" - Average rainfall in March:
2.44" - Average rainfall in April:
2.8" - Average rainfall in May:
3.11" - Average rainfall in June:
2.68"
- Average rainfall in July:
3.03" - Average rainfall in August:
3.78" - Average rainfall in September:
2.01" - Average rainfall in October:
2.56" - Average rainfall in November:
2.36" - Average rainfall in December:
2.72"
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
Fairfax, VA
- Average rainfall days in January:
10.4 days - Average rainfall days in February:
10.7 days - Average rainfall days in March:
13.8 days - Average rainfall days in April:
15.6 days - Average rainfall days in May:
17.3 days - Average rainfall days in June:
14.6 days
- Average rainfall days in July:
17 days - Average rainfall days in August:
17.3 days - Average rainfall days in September:
13.1 days - Average rainfall days in October:
12.2 days - Average rainfall days in November:
9.1 days - Average rainfall days in December:
10.9 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
Fairfax, VA
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
Fairfax, VA
- Average snowfall days in January:
5.6 days - Average snowfall days in February:
5.3 days - Average snowfall days in March:
3.3 days - Average snowfall days in April:
0.2 days - Average snowfall days in May:
0 days - Average snowfall days in June:
0 days
- Average snowfall days in July:
0 days - Average snowfall days in August:
0 days - Average snowfall days in September:
0 days - Average snowfall days in October:
0 days - Average snowfall days in November:
0.5 days - Average snowfall days in December:
3.1 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 / Average sunshine
Fairfax, VA
- Average daylight in January:
9h and 48min - Average daylight in February:
10h and 48min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 12min - Average daylight in May:
14h and 18min - Average daylight in June:
14h and 48min
- Average daylight in July:
14h and 36min - Average daylight in August:
13h and 36min - Average daylight in September:
12h and 24min - Average daylight in October:
11h and 12min - Average daylight in November:
10h and 6min - Average daylight in December:
9h and 30min
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 January:
5h and 12min - Average sunshine in February:
5h and 12min - Average sunshine in March:
6h and 54min - Average sunshine in April:
9h and 0min - Average sunshine in May:
9h and 6min - Average sunshine in June:
10h and 18min
- Average sunshine in July:
10h and 48min - Average sunshine in August:
10h and 12min - Average sunshine in September:
9h and 0min - Average sunshine in October:
5h and 42min - Average sunshine in November:
5h and 48min - Average sunshine in December:
5h and 12min
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
Fairfax, VA
- Average sunshine days in January:
17.4 days - Average sunshine days in February:
14.2 days - Average sunshine days in March:
14.5 days - Average sunshine days in April:
12.6 days - Average sunshine days in May:
11.9 days - Average sunshine days in June:
13.2 days
- Average sunshine days in July:
11.3 days - Average sunshine days in August:
11.6 days - Average sunshine days in September:
15.7 days - Average sunshine days in October:
17.1 days - Average sunshine days in November:
19.6 days - Average sunshine days in December:
16.9 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
Fairfax, VA
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
Fairfax, VA
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
Fairfax, VA
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).
