Other facts from our historical weather data: When is the rainy season in Roi Et? Rainy season in Roi Et occurs in the months of May, June, July, August and September. Does Roi Et have a dry season? Yes, the months of January, February and December are very dry. Which is the hottest month in Roi Et? April has an average maximum temperature of 37°C (99°F) and is the hottest month of the year. Which is the coolest month in Roi Et? The coolest month is January with an average maximum temperature of 31°C (88°F). Which is the wettest month in Roi Et? September tops the wettest month list with 271mm (10.7 in) of rainfall. Which is the driest month in Roi Et? December is the driest month with 6mm (0.2 in) of precipitation. Which is the sunniest month in Roi Et? December is the sunniest month with an average of 259 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.