Planning for the weather is a good way to make your trip to La Rosiere relaxing and enjoyable, especially when you're splurging. The hottest months are usually July and August with an average temp of 55°F, while the coldest months are January and February with an average of 26°F. The rainiest months in La Rosiere are May, December, November, and January, with each month seeing an average of 7 inches of rainfall.