Other facts from our historical weather data: When is summer in Susanville?The hottest season / summer takes place in June, July, August and September. Does Susanville have a dry season? Yes, the months of May, June, July, August and September are very dry. Which is the warmest month in Susanville? July has an average maximum temperature of 32°C (90°F) and is the warmest month of the year. Which is the coldest month in Susanville? The coldest month is December with an average maximum temperature of 6°C (43°F). Which is the wettest month in Susanville? December tops the wettest month list with 70mm (2.8 in) of rainfall. Which is the driest month in Susanville? August is the driest month with 4mm (0.2 in) of precipitation. No idea where to travel to this year? We have a tool that recommends destinations based on your ideal conditions. Find out where to go with our weather planner.