Other facts from our historical weather data: Which is the warmest month in Clam Gulch? August has an average maximum temperature of 16°C (61°F) and is the warmest month of the year. Which is the coldest month in Clam Gulch? The coldest month is January with an average maximum temperature of -2°C (28°F). Which is the wettest month in Clam Gulch? September tops the wettest month list with 151mm (5.9 in) of rainfall. Which is the driest month in Clam Gulch? March is the driest month with 53mm (2.1 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.