Other facts from our historical weather data: When is summer in Turrialba?The hottest season / summer takes place in May, June, August and September. Which is the warmest month in Turrialba? September has an average maximum temperature of 24°C (75°F) and is the warmest month of the year. Which is the coldest month in Turrialba? The coldest month is February with an average maximum temperature of 22°C (72°F). Which is the wettest month in Turrialba? October tops the wettest month list with 465mm (18.3 in) of rainfall. Which is the driest month in Turrialba? March is the driest month with 126mm (5 in) of precipitation. Which is the sunniest month in Turrialba? March is the sunniest month with an average of 284 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.