Idaho weather in September
One place stands in for Idaho here — these are Boise's numbers, not a statewide average.
Based on 1 weather station, in Boise. One station — Boise sits in the state’s warm southwestern valley, so the mountain towns and the panhandle run colder and snowier than these rows.
Boise & the Treasure Valley
Highs near 80°, nights around 53°, and 0.4 in of rain in a typical September.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Boise | 80° / 53° | 1 | Peach season, cool evenings, and the valley finally breathing. |
Each place above has its own page for the full story — what the month feels like, what to pack, and whether the timing is right.