Nagano Weather Forecast

Markedly. Karuizawa and Kamikochi sit between 900m and 1,500m, so August days run in the mid-20s°C with cool dry nights. That is the whole reason Karuizawa exists as a summer retreat, and it still works.

Late December to early April at Hakuba and Shiga Kogen, with the deepest and driest snow through January and February. The Jigokudani snow monkeys are best on the same schedule, when steam against snow is at its most striking.

One layer more than you think, in every season. The daily temperature swing is large — a 28°C afternoon in the Kiso valley can fall to 14°C after dark — and mountain weather turns faster than a prefecture-wide forecast can show.