Planning for the weather is a good way to make your trip to San Blas relaxing and enjoyable, especially when you’re splurging. The hottest months are usually October and November, with an average temperature of 11°C, while the coldest months are July and June, with an average of 9°C. The rainiest months in San Blas are February, December, January and March, with each month seeing an average of 347 mm of rainfall.