Planning for the weather is a good way to make your trip to Yilan relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 28°C, while the coldest months are January and February, with an average of 17°C. The rainiest months in Yilan are October, November, September and December, with each month seeing an average of 287 mm of rainfall.