Idaho weather by county

44 counties · records since 1895, through September 2026.

Idaho in September 2026

5 of 44 counties ran at least 1° warmer than usual in September 2026, and 18 ran at least 1° cooler.
Warmest against its own records: Jefferson County (12th-warmest September of 132). Coolest: Boundary County (52nd-coldest).
Wettest September against its records: Lewis County, 2.7 inches (13th-wettest).
37 of 44 counties were in moderate drought or worse on NOAA's Palmer reading for September.
Since 1970 the state's counties have warmed about 0.5° per decade on average, Franklin County the most at 0.7°.

This week's forecast against the usual, and every month since 1895, for all 44 counties in Idaho. None had a top-10 warm September in 2026.