Other facts from our historical weather data: Which is the hottest month in Cosón? September has an average maximum temperature of 32°C (90°F) and is the hottest month of the year. Which is the coolest month in Cosón? The coolest month is January with an average maximum temperature of 29°C (84°F). Which is the wettest month in Cosón? May tops the wettest month list with 145mm (5.7 in) of rainfall. Which is the driest month in Cosón? February is the driest month with 58mm (2.3 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.