In September, Oshawa typically sees daytime highs of 20.8°C and overnight lows around 11.0°C. Compared to the annual average high of 11.9°C, September runs +8.9°C.
September in Oshawa averages a daytime high of 20.8°C and an overnight low of 11.0°C.
September runs +8.9°C compared to Oshawa's annual average high of 11.9°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 20.8°C and cooler evenings around 11.0°C.