Conditions on this page are recalculated from the latest forecast every time it is opened, for the current date in the location's own time zone.
Feels-like under -25°C at the top — frostbite in under 20 min on exposed skin. Full base layers, face cover, chemical hand-warmers — coldest powder is here. Surface turns to mush. Refreeze overnight = ice tomorrow. Spa day candidate. Softens groomers and edges of runs — pleasant but no off-piste change. Off-piste opens up. Set the alarm — untracked lines disappear by 11:00. Storm-cycle day. Fills back in all morning. Plan plan B for wind hold. Ideal base-area temperature sits at -8 to -2°C. Cold enough to preserve snow quality throughout the day, warm enough that riders stay comfortable without aggressive heat-management. Above +2°C the snow surface starts breaking down by mid-morning; below -15°C the experience moves from skiing to surviving without face cover and chemical warmers. A 0–100 score from a pure function with six inputs: base-area temperature (feeds a wind-chill calculation), new snow in 24h, base depth, top-of-lift wind, visibility and next-hour precipitation. The score starts at 60 — skiing has more downside than upside, so the bar is set lower than running. Heavy new snow on a deep base adds the most; gale-force wind, whiteout or rain-on-snow subtract the most. Base depth is the difference between a "full mountain open" day and a "groomers only" day. Below 70 cm, rocks and shrubs sit just under the surface off-piste — destroying ski bases and risking injury. Above 120 cm, the full mountain inventory unlocks. Niseko's 320 cm mid-season base is one of the deepest in the world; early-season alpine resorts often launch with 40–60 cm. Wind chill calculated against the top-of-lift air temperature and sustained wind speed. At -10°C with 40 km/h wind, the chair-lift "feels-like" is around -22°C — that is the temperature your face actually experiences. The Decision Card shows feels-like below the archetype label. Use it — not the base-area air temperature — to decide kit. Day -3: directional only ("storm cycle on Thursday"). Day -1: lock the early alarm if 15+ cm forecast at 22:00 the night before. Day 0: re-check the morning bulletin — most resorts publish "new overnight" at 06:00 and lift status updates at 07:30. The Decision Card lets you sandbox the forecast values; the Live Resorts Grid shows current Open-Meteo conditions. Look at three signals: (1) elevation — base above 1800 m and top above 3000 m guarantees cold-temperature reliability; (2) latitude / continentality — Hokkaido and the Rockies hold snow longer than the maritime Alps; (3) historical opening dates — resorts that open in November every year for 10+ years have the inventory to keep skiers happy through January thaws. Top-of-lift wind above 60 km/h is statistically the #1 ruiner of planned days. It triggers cascading lift holds, scours the off-piste clean, blows powder into ice plates on traverses, and turns chair-lift rides into endurance tests. Whiteout visibility is #2 — flat light above tree-line makes terrain reading dangerous. Rain on snow is the unrecoverable #3. 15 cm is the threshold where off-piste opens up meaningfully — soft turns everywhere, side-country lines fill back in. 30+ cm is a storm-cycle day where untracked stays available all morning if the lifts run. Below 5 cm is a "refresh" — pleasant but not the experience anyone took a powder-day off work for. Niseko (Hokkaido) averages 14m+ of seasonal snowfall thanks to Siberian cold air crossing the Sea of Japan — daily Japow is climate, not luck. Hakuba is Niseko's less-crowded sibling. Whistler, Jackson Hole and the Wasatch (Park City, Alta, Snowbird) deliver the deepest sustained North American base depths. Verbier and St. Anton dominate European storm-cycle skiing. Inside marked resort boundaries on groomed runs: no. The moment you cross a rope line, drop into untracked side-country, or ski with a guide: beacon, shovel, probe are mandatory, plus the training to use them. Modern transceivers (Mammut Barryvox, BCA Tracker4) are 350–450 EUR; the training course is 200 EUR. Both are non-negotiable for off-piste. Merino base layer, mid-weight fleece, insulated shell jacket, insulated pants, mittens (warmer than gloves) with chemical hand-warmers, balaclava or full face buff under helmet, ski socks (NEVER cotton). Goggles must fit the helmet — bare skin between is the #1 frostbite spot.
Scores are capped by dealbreakers — heavy rain, dangerous wind, thick fog or hazardous UV pull a day down no matter how pleasant the rest of the numbers look. Forecast data is Open-Meteo; solar and lunar values are computed for Ski Decision Guide's own coordinates and time zone. Full details on the methodology page.