Other facts from our historical weather data: Which is the warmest month in Yarmouth? August has an average maximum temperature of 19°C (66°F) and is the warmest month of the year. Which is the coldest month in Yarmouth? The coldest month is January with an average maximum temperature of 3°C (37°F). Which is the wettest month in Yarmouth? December tops the wettest month list with 158mm (6.2 in) of rainfall. Which is the driest month in Yarmouth? August is the driest month with 93mm (3.7 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.