Annandale experiences a humid subtropical climate (Köppen climate classification *Cfa*), featuring four distinct seasons.
* **Summer:** Summers are hot and humid, with average high temperatures in July and August reaching the upper 80s to low 90s Fahrenheit (30–34 °C). High humidity can make the heat index significantly higher. * **Winter:** Winters are generally cool to cold. January average highs are in the low 40s °F (5–6 °C), with lows dropping into the upper 20s °F (-2 °C). Annual snowfall averages around 15–20 inches, though it varies highly from year to year. * **Spring and Fall:** These are widely considered the best times to visit, offering mild temperatures, lower humidity, and beautiful foliage (cherry blossoms and dogwoods in spring; vibrant autumn colors in fall). * **Precipitation:** Rainfall is distributed fairly evenly throughout the year, averaging about 43 inches annually. Severe weather occasionally includes summer thunderstorms and the remnants of Atlantic hurricanes, though major natural disasters are rare.