Most of Japan's Ski Slopes Face North or East. It Tells You Less About the Snow Than You'd Think, Except in March.

We measured which way every mapped run descends at 181 Japanese ski areas. At the middle one, 76% of the vertical faces north or east. That barely predicts snow quality: the weather decides what falls. Where direction matters is after the snow stops, and above all in spring.

A slope that faces away from the sun keeps its snow colder and for longer, and ski areas tend to be built that way. Worldwide, 67% of the vertical on the world’s ski runs descends toward the pole, according to a study of OpenStreetMap data (OpenSkiStats).

We measured the same thing for Japan: which way every mapped run descends, at the 181 Japanese ski areas that have eight or more runs on the map. Then we set it beside the snow we measure at each one.

Japan’s slopes face north and east

At the middle ski area, 76% of the vertical on the runs descends to the north or east. At 65% of ski areas, more than half does. North on its own is a smaller share than you might expect, 20% at the middle ski area, so most of that is east.

The names most visitors know show the spread:

Ski areaNorthEastSouthWestSnow quality (of 395)
APPI56%38%2%4%33rd
Rusutsu44%42%8%6%125th
Nozawa Onsen30%10%13%48%133rd
Zao Onsen29%6%8%57%78th
Hakuba Happo-One25%66%6%3%102nd
Kiroro21%2%6%71%24th
Furano12%74%12%1%115th
Niseko United10%44%39%7%38th
Myoko Suginohara1%50%48%2%48th

Share of the vertical on the runs, by the direction the run descends toward.

It says little about how good the snow is

Across the 181 ski areas, the share of north- and east-facing vertical barely tracks our snow-quality score, and what small link there is runs the wrong way. Ski areas that face north and east more are, if anything, a little warmer on snowy days (rank correlation −0.14), and they score a little lower on quality (−0.21).

The reason is what the score measures. It is built from the weather when it snows: the temperature, how often it rains instead, how often a big fall comes, and the wind (how the score works). That is set by the air that arrives over the mountain, not by the direction the slope faces. Kiroro is the clearest case. Seventy-one per cent of its vertical faces west, the sunniest direction in the afternoon, and it still ranks 24th of 395 for snow quality, with snow falling at −8.0 °C and rain on 6% of winter days.

So a north-facing slope does not turn a wet climate into a dry one. It protects snow that has already fallen.

Where it does matter: after the snow stops, and in spring

Direction starts to matter once the snow stops falling. On a clear day, sun on a south- or west-facing slope turns fresh snow heavy by the afternoon and crusty overnight. North-facing snow stays cold. In midwinter Japan the next storm usually resets everything within days. From late February, as the sun climbs higher, the difference between aspects grows, and for a March trip it is worth choosing terrain that faces away from the sun.

These are the ski areas where at least 60% of the vertical faces north or east, ranked by how much snow March brings:

Ski areaMarch snowfallNorth + eastSnow quality
Tateyama Sanroku114 cm84%164th
Okutadami Maruyama105 cm95%69th
Hakuba 4797 cm86%19th
Tsugaike97 cm68%23rd
Hakuba Iwatake97 cm65%47th
Mitsumata (Kagura)96 cm85%132nd
Hakuba Norikura93 cm65%35th
ARAI87 cm88%155th

March snowfall is the average for March over the last 8 to 12 winters.

For a March trip, four Hakuba valley resorts (Hakuba 47, Tsugaike, Iwatake and Norikura) combine the three things you want: close to 100 cm of new snow in March, most of the terrain facing north or east, and snow-quality scores in the top 50.

The best of both

These ski areas face mostly north or east and rank in the top 50 for snow quality:

Ski areaNorth + eastSnow qualitySnow-day temperatureTypical winterWorst of 12
Tengendai Kogen76% (north 74%)9th−7.8 °C379 cm151 cm
Tashiro (Kagura)82%12th−7.1 °C447 cm241 cm
Shiga Kogen Kumanoyu92%14th−8.9 °C333 cm214 cm
Okushiga Kogen88%18th−8.2 °C333 cm214 cm
Hakuba 4786%19th−4.5 °C668 cm380 cm
Sapporo Kokusai84%25th−7.8 °C331 cm209 cm
APPI94%33rd−5.2 °C377 cm167 cm
Blue Resort Norikura97%36th−7.7 °C317 cm134 cm
Hachimantai Shimokura90%46th−5.3 °C329 cm167 cm

Of the 181 ski areas, only two have at least 60% of their vertical facing due north and also rank in the top 50 for snow quality: Tengendai and Shiga Kogen Kumanoyu. Tengendai’s runs descend 74% northward, where the typical Japanese ski area has a fifth, and it ranks 9th for snow quality. Kumanoyu is 65% north-facing and the coldest on this list. Tengendai’s catch is its floor: in its leanest winter it had 151 cm. Hakuba 47 is the opposite trade, a little less cold, but with one of the deepest floors in the country.

How this was measured

Slope direction comes from the runs mapped on OpenStreetMap, as processed by OpenSkiMap (© OpenStreetMap contributors, ODbL 1.0). We split each run into short segments and keep the ones that go downhill. Each segment counts toward the compass direction it descends toward (north, east, south or west), weighted by how much height it loses, so steep pitches count for more than flat traverses. This is the same approach OpenSkiStats uses. Only ski areas with eight or more mapped runs are included, 181 in all. Niseko’s figures are for the whole Niseko United area, which the map draws as one ski area.

This measures the mapped runs, not the whole mountain, and how finely ski areas are mapped varies. We have no measurement of how snow differs between aspects at a given ski area. What is here is the shape of the terrain and the weather when it snows, not a direct measurement of snow on each slope.

Snow quality, snow-day temperature and rain use our snow-quality score for Japan’s 395 ski areas (details). Snowfall adds up each day’s snowfall over each of the last twelve winters (December to March, 2014/15 to 2025/26) using the ERA5 reanalysis. March snowfall is the average for March over the last 8 to 12 winters. Neighbouring ski areas can share one cell of the model’s grid, which is why Hakuba 47, Tsugaike and Hakuba Iwatake have the same snowfall figures. The model understates mountain snow (details), so use the figures to compare ski areas.

The rank correlations are Spearman correlations across the 181 ski areas. A value near zero means the two measures barely move together.

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