You might spend a lot of your vacation inside, but if you're planning to venture beyond the casino, looking at local weather trends is a good idea. The hottest months are usually August and July with an average temp of 74°F, while the coldest months are January and February with an average of 42°F. The rainiest months in Hatsukaichi are July, June, August, and September, with each month seeing an average of 11 inches of rainfall.