In September, Idaho Falls typically sees daytime highs of 23.8°C and overnight lows around 4.8°C. Compared to the annual average high of 14.5°C, September runs +9.3°C.
September in Idaho Falls averages a daytime high of 23.8°C and an overnight low of 4.8°C.
September runs +9.3°C compared to Idaho Falls's annual average high of 14.5°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 23.8°C and cooler evenings around 4.8°C.