Typical operating window
December–MarchThe base normally develops in late autumn and early winter, with midwinter offering colder surfaces.Verified planning context
Snow, weather and avalanche context
Historical patterns help you compare trips. They do not predict your week or replace the operator's daily decisions.
Strongest comparable snow evidence
252 cm median · 179–329 cm interquartile rangeNOAA GHCN station USC00104845, Ketchum RSTier B · observed reference · moderate confidenceSnow character
continentalThe continental snowpack can produce light powder and persistent weak layers during prolonged cold periods.Public avalanche information
Sawtooth Avalanche CenterUse the forecast region that contains the planned terrain. The operator makes the commercial decision.Weather and flight context
Pacific systems lose moisture inland, producing intermittent storms separated by dry continental weather.
- Valley fog and inversion
- Ridge wind
- Thin coverage during dry cycles
Meteorological reference area
Sun Valley and central Idaho reference area
- Includes
- Sun Valley and nearby central Idaho reference sites.
- Excludes
- The wider Idaho mountain climate as one value.
- Elevation
- No verified operator-terrain elevation band is public. Each evidence value retains its site elevation.
Evidence pack
Measurements, claims and gaps stay separate.
Tier BValley reference-station snowfall252 cm median · 179–329 cm interquartile range
- Site
- NOAA GHCN station USC00104845, Ketchum RS · 43.6842, -114.3603 · 1795 m · 2 km from the catalogue reference
- Period
- July–June snow years, 1991/92–2019/20
- Completeness
- 24 of 29 snow years had at least 330 valid daily snowfall values.
- Method
- Quality-flagged daily SNOW values summed by snow year; incomplete years excluded.
- Limitation
- The lower Ketchum station does not represent Bald Mountain or heli-ski terrain.
- Global Historical Climatology Network DailyNOAA National Centers for Environmental Information · accessed 2026-08-25
Tier CModelled snowfall water equivalent387 mm SWE median · 340–446 mm interquartile range
- Site
- Sun Valley ERA5-Land grid cell · 43.7000, -114.4000 · 3.9 km from Sun Valley reference point
- Period
- Calendar years 1991–2020
- Completeness
- 360 monthly means; all 30 calendar years contain 12 values.
- Method
- ERA5-Land monthly mean daily snowfall accumulation was multiplied by calendar days and 1,000, then summed by calendar year.
- Limitation
- This reference area supports evidence discovery and comparison. It is not an operating-area or tenure boundary. The sampled gateway cell can differ substantially from ski elevations. This unadjusted 0.1° reanalysis grid cell is not an observation, snow depth, or terrain-wide total. Grid elevation and wind redistribution can cause substantial local bias.
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
Tier EPublished commercial snowfall claim200 in / 5.08 m resort claim
- Site
- Sun Valley Resort; measurement site unspecified
- Period
- Baseline period not published by the source
- Completeness
- The source does not publish the underlying observation record.
- Method
- Interested-source claim. Heliski International has not reconstructed the measurement series.
- Limitation
- This resort figure is a local marketing claim, not a normal for the operator’s full heli-ski terrain.
- Sun Valley mountain factsSun Valley Resort · accessed 2026-08-25
Monthly evidence
Each cell keeps its measurement type and unit. Reanalysis water equivalent is not snow depth. Text-only cells preserve a representative data gap.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 77.2 cm snowfall | 41.3 cm snowfall | 19.7 cm snowfall | 7.6 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 0 cm snowfall | 21 cm snowfall | 84.6 cm snowfall |
Commercial operator assessment
Operator assessment process not independently verifiedThe operator must assess current snow, avalanche terrain, weather, aircraft limits, and rescue options. No private operational plan is inferred.
Sources and evidence notes
- Sun Valley mountain factsSun Valley Resort · accessed 2026-08-25
- Published operator and trip inventoryHeliski International editorial team · accessed 2026-08-25
- Global Historical Climatology Network DailyNOAA National Centers for Environmental Information · accessed 2026-08-25
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
- Sawtooth Avalanche CenterSawtooth Avalanche Center · accessed 2026-08-25
- U.S. Climate Normals 1991–2020NOAA National Centers for Environmental Information · accessed 2026-08-25