Fairfax Temperature by Month
Fairfax, Virginia, United States of America has an average annual maximum temperature of 19°C (66°F), ranging from 6°C (43°F) in January to 30°C (86°F) in July. Below you'll find a full monthly breakdown and a comparison with cities worldwide.
Fairfax Monthly Temperatures
The climate in Fairfax is dynamic, ranging widely from chilly in winter to very warm in summer. Nights are significantly colder, with lows dropping from 20°C (68°F) in July to -4°C (25°F) in January.
The chart below illustrates the average maximum day and minimum night temperatures in Fairfax by month:
Temperatures tend to bottom out between 4 AM and 6 AM, then climb to their daily peak around 3 PM. July, the warmest month, sees 279 hours of sunshine.
The chart below shows the average temperature throughout the year:
Temperature: Fairfax vs the United States of America
The map below shows the annual temperature across the United States of America. You can also select individual months if you want to compare a specific time of year.
very warm
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moderate
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Fairfax vs World: Temperature Compared
Fairfax's average annual maximum temperature is 19°C (66°F). To put that in context, here's how it compares to a few well-known destinations:
Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.
On the cooler end, Oslo, Norway averages just 10°C (50°F) annually, with pleasant summers but long, cold winters.
Seoul, South Korea averages 18°C (64°F) a year, with four clear seasons, cold winters, and hot humid summers.
Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.
What Does the Temperature Feel Like in Fairfax?
Temperature alone doesn't tell the whole story — humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.
In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.
In Fairfax, January is the coolest month, with average highs of 6°C (43°F) and humidity around 62% — considered high. In July, the warmest month, temperatures average 30°C (86°F) with 67% humidity — conditions that feel high. For a full picture, see our humidity page.
Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.
The readings come from a range of sources — land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.
For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained — so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.
For more on Fairfax's weather — including monthly rainfall, sunshine hours, and humidity — visit our Fairfax climate page.
