Ice Dam Prevention in Montana

In Montana, local ice dams deadlines run from Sep 15 to Oct 16, with a median around Sep 15 — a spread of weeks that a single statewide date would miss. Find your city below; each links to local freeze odds, a live 10-day outlook, and a checklist.

Jump to a city

Notable cities

Billings — earliest deadline in the state
Missoula — latest deadline in the state
Bozeman — near the state median

All Montana cities

City	Local deadline	Median first 28°F
Billings	Sep 15	Oct 12	View →	Checklist
Great Falls	Sep 15	Oct 11	View →	Checklist
Bozeman	Sep 15	Oct 3	View →	Checklist
Helena	Sep 15	Oct 7	View →	Checklist
Missoula	Oct 16	Oct 12	View →	Checklist

Back to the national Ice Dam Prevention guide, or see the methodology.

Data: NOAA NCEI 1991–2020 U.S. Climate Normals; live outlook by Open-Meteo. Last updated: July 11, 2026.