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 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.