How we calculate historical snowfall in Japan

STEP 1

Thirty winters of station records

We use daily snowfall from the nearest Japan Meteorological Agency station, November to April, from 1996/97 to 2025/26. Where two stations lie within 15km of the resort, we use both and give the nearer one more weight. Each calendar day is averaged across every winter with a valid reading. Missing days are never filled in.

STEP 2

Adjusted to mid-mountain

These stations sit in the valley towns below the lifts. We adjust each figure by 10% per 100m, up to the midpoint between the resort's base and its top lift. The rate is in line with airborne laser surveys in Hokkaido, which found snow depth rising in a straight line with height below the treeline (Nishihara and Tanise, 2016).

STEP 3

Valley rain that falls as snow

When it rains at the station, it is often cold enough to snow at mid-mountain. For every hour of precipitation we estimate the mid-mountain temperature and, where it is cold enough, count that precipitation as snow. This part is modelled from the station's own temperature and precipitation records. It is not measured.

EXAMPLE: HAKUBA HAPPO-ONE

The Hakuba station, at 703m, records about 600cm a winter. Mid-mountain is 1,296m, which is 593m higher. We add 59%, giving about 960cm. Valley rain that falls as snow adds about 200cm, for a 30-winter average of about 1,160cm.

WHY JAPAN IS DIFFERENT

In Europe we start from a global climate model and correct it against mountain stations. That model doesn't capture Japan's heavy sea-effect snowfall, so in Japan we start from measured snowfall instead.

GOOD TO KNOW

Natural snowfall only, no snowmaking.
Snowfall, not snow depth on the ground.
A mid-mountain estimate, built on measured station figures.
On its own scale. Don't compare Japanese totals directly with European ones.
A guide for comparing resorts, not exact to the centimetre.
Historical, not a forecast. Always check the mountain forecast before you travel.

RELIABILITY SCORE

The score counts winters reaching at least 350cm, the same benchmark we use everywhere.

Stations and heights by resort

Resort	Station	Distance	Station height	Mid-mountain	Uplift
Niseko Grand Hirafu	Kutchan	6km	176m	730m	+55%
	Rankoshi	14km	39m	730m	+69%
Rusutsu	Kimobetsu	6km	264m	697m	+43%
Furano	Furano	3km	174m	655m	+48%
Hakuba Happo-one	Hakuba	2km	703m	1,296m	+59%

Mid-mountain is the midpoint between each resort's published base and top lift heights. Niseko uses two stations because both lie within 15km. Kutchan, the nearer one, carries about 70% of the weight.

Known limitations

These figures are a strong guide to how snowy a resort's winters are, not a precise measurement. The main limits:

The uplift is one rule. It is in line with surveys of snow depth in central Hokkaido and is applied to every resort the same way. The true rate will vary from mountain to mountain.
The valley-rain estimate is modelled. It uses hourly temperature and precipitation and a standard temperature drop with height. Tested against the stations' own snowfall, it matched one station closely and the others less well, so treat it as an estimate.
Stations sit in the valley. Each can be several kilometres from the slopes and may not see exactly the same weather.
Niseko blends two stations. Rankoshi records about 70% of Kutchan's snowfall, and the figure is weighted towards Kutchan.
Recent winters have been less snowy than the 30-winter average.
One station changed method. Kutchan's snowfall measurement changed in October 2005. A comparison with the neighbouring station showed no material shift.

Data sources and attribution

CHAMPOW's figures are our own analysis. They are not official statistics from the provider below.

Data	Source and licence
Station snowfall	Japan Meteorological Agency (JMA) past weather data, processed by CHAMPOW · JMA website terms of use
Uplift rate	Nishihara, T. and Tanise, A. (2016), Civil Engineering Research Institute for Cold Region

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