In September, Reston typically sees daytime highs of 26.4°C and overnight lows around 13.8°C. Compared to the annual average high of 18.8°C, September runs +7.6°C.
September in Reston averages a daytime high of 26.4°C and an overnight low of 13.8°C.
September runs +7.6°C compared to Reston's annual average high of 18.8°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 26.4°C and cooler evenings around 13.8°C.