If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in San Juan de Pasto: The hottest months are usually September and August, with an average temperature of 17°C, while the coldest months are August and July, with an average of 17°C. The rainiest months in San Juan de Pasto are April, March, May and November, with each month seeing an average of 465 mm of rainfall.