Other facts from our historical weather data: Which is the warmest month in Jasper? July has an average maximum temperature of 18°C (64°F) and is the warmest month of the year. Which is the coldest month in Jasper? The coldest month is December with an average maximum temperature of -10°C (14°F). Which is the wettest month in Jasper? July tops the wettest month list with 124mm (4.9 in) of rainfall. Which is the driest month in Jasper? February is the driest month with 46mm (1.8 in) of precipitation. Which is the sunniest month in Jasper? July is the sunniest month with an average of 252 hours of sunshine. 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.