In September, Arlington Heights typically sees daytime highs of 23.4°C and overnight lows around 12.4°C. Compared to the annual average high of 14.3°C, September runs +9.2°C.
September in Arlington Heights averages a daytime high of 23.4°C and an overnight low of 12.4°C.
September runs +9.2°C compared to Arlington Heights's annual average high of 14.3°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 23.4°C and cooler evenings around 12.4°C.