Planning for the weather is an important factor for making your trip to Twain Harte a success, especially when you’re splurging. The hottest months are usually July and August with an average temp of 72°F, while the coldest months are February and December with an average of 43°F. The rainiest months in Twain Harte are December, March, January, and February, with each month seeing an average of 8 inches of rainfall.