Virginia has a four-season climate with occasional snow in winter, and warm, humid summers.
NPS Photo
The park's proximity to the Chesapeake Bay and the Blue Ridge Mountains greatly impacts the climate of the area.
Mean annual temperature is about 55 degrees (F) and ranges from 42 to 65.
The coldest period, when minimum temperatures average 21 degrees, occurs in late January. Snowfall is nearly 24 inches on average, but varies greatly from season to season. Snowfalls of four inches or more occur only twice each winter on average. Late July is the warmest period, when mean maximum temperature may reach 88 degrees.
Annual precipitation ranges from 25-55 inches. Rainfalls of over 10 inches in a 24-hour period have been recorded during the passage of tropical storms. Prevailing winds are from the south except during winter, when they are from the northwest. The highest average wind speed is in March.
While today's temperature and precipitation is weather, the weather over a long span of time is the climate of the region. Scientists track how the climate is changing over time and its effects in the park. For example, we know that average temperatures and sea levels have been rising for many years. In Manassas, scientists have studied the park's waterways and tracked metrics including pH and oxygen levels. Large scale changes have impacts as well as more local changes. Urbanization around the park has many effects, and has measurably impacted sensitive species including fish.
