Cusco can be visited all year round, but it depends what do you want to do.

Summer is from December to March but, it is the rainy season in the Highlands.During February the Inca Trail is closed for maintenance. You can still visit Machu Picchu and many other sites. You can also do one of the other available treks if you do not mind getting wet.The good thing during the rainy season is the warm weather at day time and you will not feel to cold at night. Even if it rains it will normally be a heavy shower and then the sun will come out again.In addition, the mountains will be green with the potatoes and corn plantations. Full of flowers and many colors.

Most popular time to visit Cusco is between June and August. It is recommended to come in April or May or September to October, just after and before the rainy season and the tourist crowds. Be sure to make reservations way in advance to secure your train tickets and your space on the Inca Trail. (for more info on the Trail, see the Peru inside page ).The sun is always out in the highlands, but it will be chilly in the afternoons and quite cold during winter at night. It normally does not rain during winter.

Dress  with clothing in layers ( t shirt, long sleeve shirt, sweater, jacket) so you can "peel" them off as it gets warmer and put them back on when it gets colder. Bring a small backpack to carry your clothing and tourist apparel. Casual clothing is all what you need when visiting and going to restaurants.