Other facts from our historical weather data: Which is the warmest month in Rocky Mountain National Park? July has an average maximum temperature of 19°C (66°F) and is the warmest month of the year. Which is the coldest month in Rocky Mountain National Park? The coldest month is February with an average maximum temperature of -3°C (27°F). Which is the wettest month in Rocky Mountain National Park? April tops the wettest month list with 127mm (5 in) of rainfall. Which is the driest month in Rocky Mountain National Park? June is the driest month with 29mm (1.1 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.