Considering the very high altitude, the weather on the Inca Trail is relatively mild all year round. The rainy, cooler season is between November to March; the warmer, dry season is from April to October. The average annual minimum temperature ranges between 5°C and 11°. In the months of June, July and August the temperature can drop below zero, at higher altitudes overnight. The annual maximum temperature generally ranges between 20°C to 26°.
No matter what the season, the temperatures can still vary quite a bit on the trail. Is is very important to bring everything on the equipment list.