September weather forecast and climate
Idaho, USA

Flag of Idaho, USA
Flag of Idaho, USA

Weather in September

September sees a transition to the beautiful autumn season in Idaho, with average high temperatures in the 69°F (20.6°C) to 83°F (28.3°C) range. The nights are on the colder side in the average zone of 26°F (-3.3°C) to 43°F (6.1°C) and even freezing in the hills. Lewiston in the north registers between 51°F (10.6°C) to 78°F (25.6°C), while Driggs in the east is relatively cooler between 37°F (2.8°C) to 69°F (20.6°C).
Thunderstorms occasionally extend to the early fall season, but the rainfall is moderate at best. The daily sunshine lasts for 8 hours, which makes summer clothing relevant in early fall days. Fall is the time to explore colors and enjoy the beauty of nature.
The conditions cool down significantly by mid-September, which makes it an ideal time to soak in one of the many hot springs. Scenic byways and rural roads offer unmatched natural beauty but wear a jacket or sweater during the breezy evenings. A September visit to Idaho offers one of the best weather conditions of the year.


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