Planning for the weather is a good way to make your trip to Dunham relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 17°C, while the coldest months are January and February, with an average of -6°C. The snowiest months in Dunham are January, December, March and February, with each month seeing an average of 39 cm of snowfall.