Planning for the weather is an important factor for making your trip to Ishiwaki a success, especially when you're splurging. The hottest months are usually August and July, with an average temperature of 21°C, while the coldest months are February and January, with an average of 0°C. The rainiest months in Ishiwaki are July, December, August and November, with each month seeing an average of 187 mm of rainfall.