Kusatsu Has 66 Inns and 73 Days of Deep Snow. Hirayu Has 46 Inns and 130.

Search for snow and hot springs in Japan and you get photographs. Steam, a wooden bath, deep snow on the roof. What you do not get is the one thing you need before booking: when is that snow actually there, and for how long.

Everyone answers where. Nobody answers when.

So we measured it. Snow depth at 24 Japanese hot spring towns, every day across three winters, from the same reanalysis dataset we use for everything else. Two thresholds: 5 cm, which is snow on the ground, and 30 cm, which is the postcard.

Every hot spring town, by how long the snow is deep

Median of the last three winters. Sorted by days with 30 cm or more.

Hot spring town	Snow arrives	Snow gone	Days ≥5 cm	Days ≥30 cm	Inns
Hirayu Onsen	13 Nov	2 May	161	130	46
Asarigawa Onsen	7 Nov	23 Apr	158	128	6
Seki Onsen	18 Nov	23 Apr	149	124	2
Amihari Onsen	26 Nov	24 Apr	147	123	1
Akakura Onsen	18 Nov	23 Apr	148	118	31
Oze Hinoemata	12 Nov	25 Apr	165	115	6
Zao Onsen	29 Nov	6 Apr	126	103	56
Nozawa Onsen	25 Nov	13 Apr	129	91	36
Manza Onsen	18 Nov	11 Apr	123	86	7
Kusatsu Onsen	18 Nov	13 Apr	125	73	66
Onogawa Onsen	25 Nov	7 Apr	125	68	53
Nikko Yumoto	4 Dec	23 Apr	127	65	39
Makado Onsen	3 Dec	25 Mar	105	20	5
Megahira Onsen	22 Dec	11 Feb	30	0	1

The range is not subtle. Megahira in Hiroshima has snow on the ground for 30 days and never reaches 30 cm. Hirayu in Gifu holds 30 cm for 130 days and still has snow in May. Both are hot spring towns with a ski area. They are not the same holiday.

The famous one is not the snowy one

Kusatsu Onsen has 66 inns — more than any town here — and 73 days of deep snow. It is the name most foreign visitors know, it has a genuinely spectacular sulphur spring, and its snow is mid-table.

Hirayu Onsen has 46 inns and 130 days. Almost nobody outside Japan books it.

Zao is the counter-example that keeps the pattern honest: 56 inns and 103 days, the strongest combination of scale and snow in the table. It is famous for its frost-covered trees, which is exactly what 103 days of deep snow produces.

Seki Onsen is the other end: 124 days, world 8th for snowfall, and two places to stay. That is not a destination, it is a trip you build around one booking.

The timing, in plain terms

Mid-January to early March is safe everywhere on this list that has snow at all. Every town above except Megahira holds 30 cm through that window in a normal winter. If you cannot control your dates, that is the window.

Late November is a gamble that depends entirely on which town. Asarigawa near Sapporo is already under snow on 7 November. Megahira does not start until 22 December — six weeks later.

April is better than most people think. Six towns still hold 30 cm on 23 April or later: Hirayu, Oze Hinoemata, Amihari, Asarigawa, Seki and Nikko Yumoto. Hirayu holds it to 2 May, which means Golden Week with snow on the ground — a combination almost no travel guide mentions because it sounds implausible.

And if the snow is the point rather than the skiing, go late. By April the ski crowds are gone, the inns are cheaper, and at these six towns the snow has not gone anywhere.

Choosing

If you want the most days of deep snow with a real town around you: Hirayu Onsen. 130 days, 46 inns, in the Okuhida valley under the Northern Alps.

If you want the famous names and will take what snow comes: Kusatsu or Zao. Zao is the better bet on snow by a wide margin.

If you are travelling from Sapporo and want the shortest trip: Asarigawa Onsen. 128 deep days, 26 km from a city of 2.5 million, and six inns — book early.

If you want to be somewhere almost nobody goes: Oze Hinoemata has the longest snow season of all at 165 days, six inns, and sits inside a national park.

What this does not tell you

Snow depth is modelled, not observed at the bath. These figures come from the ERA5 reanalysis on a 10–30 km grid, which flattens terrain. The number is representative of the valley, not measured outside a particular inn. Treat the comparison between towns as sound and any single figure as approximate.

Three winters is three winters. These are medians of 2023/24, 2024/25 and 2025/26. A mild year moves the arrival date later and the departure earlier — at some towns by weeks. See our piece on how much Japanese snow swings between winters; Hokkaido varies far less than Honshu.

We do not know which baths are outdoor. Whether a given inn has a rotenburo facing the snow is a property of the inn, and we do not hold that data. Check the inn.

A ski area is not the town. We locate each town by the ski area that carries its name, so the measurement is at the slope rather than in the village. In these valleys the difference is small but it is not zero, and it will usually mean the town has slightly less snow than the figure suggests.

How this was measured

Daily maximum snow depth from Open-Meteo historical data, ERA5 reanalysis, 1 November to 31 May across the last three completed winters. “Snow arrives” is the first day at or above 5 cm and “snow gone” the last; the day counts are days at or above each threshold. Every figure is the median across the three seasons, so one unusual winter does not set the answer.

Inn counts are places to stay within 6 km from OpenStreetMap, which undercounts small family-run inns — the real numbers are higher, but every town was counted the same way.

Snowfall ranks quoted elsewhere on this site come from the same reanalysis and carry the caveat they always do: the model runs well below what resorts report, so ranks travel better than centimetres.