When Does Snow Start in Idaho? Regional Breakdown

Idaho's snow onset varies dramatically by elevation and latitude—from October in the northern mountains to December in southern valleys.

Average First Measurable Snow (≥0.1")

Elevation: +1,000 ft ≈ 2–3 weeks earlier onset
La Niña: Earlier, snowier north/central
El Niño: Later, drier north; wetter south
Climate Trend: Onset ~1 week later per decade since 1980; more rain-on-snow events

First Flakes: Often 2–4 weeks before measurable
Ski Area Opening: Target late Nov (Sun Valley, Bogus, Schweitzer, Brundage, Tamarack, Lookout, Grand Targhee)
Road Closures: Galena Summit (ID-75), Lolo Pass (US-12), Bear Lake Summit (US-89) – monitor 511.idaho.gov

NOAA NWS – Local offices: Boise (KBOI), Spokane (KOTX), Pocatello (KPIH), Missoula (KMSO). weather.gov → "Climate" → "First Snow" tool.

Idaho snow: not if, but when and how much. Elevation decides.

Ski Trips

Wanderlust World

Wanderlust World

Region	Key Locations	Elevation	Typical Onset	Notes
Northern Panhandle	Coeur d'Alene, Sandpoint, Bonners Ferry	2,100–2,500 ft	Late Oct – Mid Nov	Lake effect off Pend Oreille; 50–70" season
North Central	Moscow, Lewiston, Grangeville	1,000–3,500 ft	Early – Mid Nov	Palouse hills; variable
Central Mountains	McCall, Stanley, Sun Valley, Driggs	5,000–7,000+ ft	Late Oct – Early Nov	High elevation; 150–300"+; ski areas open Nov
Southwest (Treasure Valley)	Boise, Nampa, Caldwell, Ontario OR	2,200–2,800 ft	Mid Nov – Early Dec	Rain shadow; 15–25" season; often rain/mix first
South Central (Magic Valley)	Twin Falls, Burley, Jerome	3,500–4,200 ft	Early – Mid Nov	Higher than Boise; 20–35" season
Southeast (Upper Snake)	Idaho Falls, Pocatello, Rexburg, Island Park	4,500–6,300 ft	Late Oct – Mid Nov	Cold air pooling; 30–60"+; Island Park = snowiest town
Salmon River / Lemhi	Salmon, Challis, Leadore	4,000–5,500 ft	Early – Mid Nov	Rain shadow; 20–40"