February brings the famous Sapporo Snow Festival and its enormous ice sculptures, though temperatures sit well below freezing and warm winter clothing is essential. June and July offer mild, low-humidity summer weather that's noticeably cooler than the rest of Japan, while September and October bring crisp air and vivid autumn colour in the surrounding mountains. Late April into May sees Hokkaido's own, later cherry blossom season.
Hokkaido experiences earthquakes from time to time, and the region has seen notable seismic activity in recent years. Note your accommodation's exits on arrival and follow any staff instructions if a quake occurs; ordinary awareness is enough for a short visit.
Winter temperatures regularly drop well below freezing with heavy snowfall and icy pavements underfoot. Wear proper winter boots with grip, dress in warm layers, and take extra care crossing streets where compacted snow and ice can be slippery.
Hokkaido has an active brown bear population, and sightings occasionally occur even near city parks, occasionally prompting temporary closures. This mainly matters if hiking outside paved tourist trails; within central Sapporo itself it's a background awareness point rather than a daily concern.