Other facts from our historical weather data: Which is the warmest month in San Juan La Laguna? March has an average maximum temperature of 25°C (77°F) and is the warmest month of the year. Which is the coldest month in San Juan La Laguna? The coldest month is January with an average maximum temperature of 23°C (73°F). Which is the wettest month in San Juan La Laguna? September tops the wettest month list with 442mm (17.4 in) of rainfall. Which is the driest month in San Juan La Laguna? January is the driest month with 21mm (0.8 in) of precipitation. Which is the sunniest month in San Juan La Laguna? March is the sunniest month with an average of 249 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.