Planning for the weather is a good way to make your trip to Nikko relaxing and enjoyable, 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 January and February, with an average of 1°C. The rainiest months in Nikko are July, September, June and August, with each month seeing an average of 262 mm of rainfall.