Hokkaido Cold Snap Oct 18: New First-Snowcap Rules in Japan

On Sunday, October 18, high pressure is expected to bring autumn sunshine to a wide area. Mornings will still be cold in northern Japan because of strong radiative cooling, when clear skies let heat escape overnight. According to Weathernews, minimum temperatures in Hokkaido are forecast to fall to near 0°C, even in urban areas.^[1]

tenki.jp's forecast from October 17 says only five locations in Hokkaido dropped below freezing on the morning of the 17th. On the morning of the 18th, 30 to 40 percent of Hokkaido's observation points could go below zero. Some places in Tohoku may also fall below zero.^[2]

Rain from fronts early in the week, then colder

Weathermap's forecast from the evening of October 17 shows rain in many areas from Monday onward because of fronts. In the second half of next week, temperatures are expected to drop a notch further and autumn will deepen. Whether high mountains get snow depends on how strong the cold air is at the time. Check the latest forecast before you head out.^[3]

How first snowcaps are recorded has changed this season

The Japan Meteorological Agency (JMA) records the first snowcap (hatsu-kansetsu, the first snow seen on a mountain top) at 44 mountains nationwide. From this season (August 1, 2026 to July 31, 2027), it no longer relies on visual checks by weather station staff. It now uses analyzed snow depth instead. This means snow cover can be determined even when the summit is in cloud or at night.^[4]

JMA's page cautions that the new method differs from the visual observation dates of previous seasons, so the records cannot be simply compared. The Japan Weather Association (tenki.jp) also says it will not give year-on-year or versus-normal differences this season. Phrases such as "earlier or later than usual" will be harder to use this season.^[4][5]

This season's first snowcap in Japan was recorded at Asahidake on October 2. According to NHK, JMA observed on the morning of the 2nd that the area near the summit of Asahidake (2,291 m), the highest peak in Hokkaido, was covered in snow.^[6]

Check the snow on the mountains with live cams

On a cold morning, you can also check the snow higher up with your own eyes. These live cams show the slopes and the mountains behind them.

For snow on mountains that JMA and others have not announced, it is safest to treat it as "snow is visible on the mountain" rather than an official first snowcap. We will post resorts that open this season on our opening information page.

Sources

Prepared with AI assistance from public sources. Always check each resort's official website for the latest information.