Planning for the weather is a good way to make your trip to San Juan de Pasto relaxing and enjoyable, especially when you’re splurging. The hottest months are usually September and August with an average temp of 62°F, while the coldest months are August and July with an average of 62°F. The rainiest months in San Juan de Pasto are April, March, May, and November, with each month seeing an average of 18 inches of rainfall.