Typical operating window
July–SeptemberFrequent Southern Alps precipitation builds winter cover, while glacier terrain retains snow beyond lower elevations.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
3.95 m published average · 2.58–5.32 m observed rangeMueller Hut electronic weather stationTier B · observed reference · low confidenceSnow character
maritimeDense storm snow near the divide can transition to dry snow in cold periods and spring corn during clear cycles.Public avalanche information
NZAA Aoraki/Mount Cook regionThe public advisory excludes commercial use. The operator must use its own formal hazard assessment.Weather and flight context
The Main Divide forces rapid uplift of moist westerly flow and produces severe alpine gradients.
- Main Divide cloud
- Severe wind and turbulence
- Glacier whiteout
Meteorological reference area
Aoraki Mount Cook program area
- Includes
- Aoraki Mount Cook program and nearby high-alpine reference sites.
- Excludes
- Tasman Glacier as a separate comparison profile when evidence is glacier-specific.
- 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 BObserved winter snowfall reference3.95 m published average · 2.58–5.32 m observed range
- Site
- Mueller Hut electronic weather station · 1818 m · Distance unavailable — the source summary does not publish station coordinates
- Period
- Ten winters; exact years are not listed in the published summary
- Completeness
- Ten-year summary; annual values and missing periods are not published on the source page.
- Method
- Earth Sciences New Zealand published mean and observed minimum-to-maximum winter snowfall.
- Limitation
- The station is below much of the ski terrain and does not measure glacier-wide accumulation.
- Winter snowfall summary from high-elevation stationsEarth Sciences New Zealand · accessed 2026-08-25
Tier CModelled snowfall water equivalent595 mm SWE median · 548–686 mm interquartile range
- Site
- Aoraki Mount Cook ERA5-Land grid cell · -43.6000, 170.1000 · 3.4 km from Aoraki Mount Cook 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
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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1.9 mm SWE | 1.6 mm SWE | 4 mm SWE | 13.3 mm SWE | 44.5 mm SWE | 81.7 mm SWE | 100.9 mm SWE | 84.6 mm SWE | 82.6 mm SWE | 64.3 mm SWE | 38.8 mm SWE | 10.8 mm SWE |
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
- WMO Climatological NormalsWorld Meteorological Organization · accessed 2026-08-25
- ERA5-Land hourly data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-25
- New Zealand Avalanche AdvisoryNew Zealand Mountain Safety Council · accessed 2026-08-25
- Published operator and trip inventoryHeliski International editorial team · accessed 2026-08-25
- Winter snowfall summary from high-elevation stationsEarth Sciences New Zealand · accessed 2026-08-25
- ERA5-Land monthly averaged data from 1950 to presentCopernicus Climate Change Service · accessed 2026-08-26
- What is the New Zealand Avalanche Advisory?New Zealand Mountain Safety Council · accessed 2026-08-25
- Mount Cook Heliski operating datesMount Cook Heliski · accessed 2026-08-25