Planning for the weather is a good way to make your trip to Otaru relaxing and enjoyable, especially when you’re splurging. The hottest months are usually August and July, with an average temperature of 18°C, while the coldest months are February and January, with an average of -5°C. The snowiest months in Otaru are January, February, March and December, with each month seeing an average of 77 cm of snowfall.