In September, Portland typically sees daytime highs of 20.6°C and overnight lows around 10.2°C. Compared to the annual average high of 12.6°C, September runs +8.0°C.
September in Portland averages a daytime high of 20.6°C and an overnight low of 10.2°C.
September runs +8.0°C compared to Portland's annual average high of 12.6°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 20.6°C and cooler evenings around 10.2°C.