Other facts from our historical weather data: Which is the warmest month in Effingham? July has an average maximum temperature of 30°C (86°F) and is the warmest month of the year. Which is the coldest month in Effingham? The coldest month is January with an average maximum temperature of 3°C (37°F). Which is the wettest month in Effingham? June tops the wettest month list with 159mm (6.3 in) of rainfall. Which is the driest month in Effingham? January is the driest month with 61mm (2.4 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.