Planning for the weather is a good way to make your trip to Waterville relaxing and enjoyable, especially when you're splurging. The hottest months are usually July and August, with an average temperature of 15°C, while the coldest months are February and March, with an average of 8°C. The rainiest months in Waterville are December, November, January and October, with each month seeing an average of 188 mm of rainfall.