Weather is only one factor, but it can really affect your travel plans, especially when you are planning a longer stay in San Martín. The hottest months are usually January and December, with an average temperature of 22°C, while the coldest months are July and June, with an average of 12°C. The rainiest months in San Martín are January, February, December and November, with each month seeing an average of 187 mm of rainfall.