What To Wear While In Machu Picchu
The best months to visit Machu Picchu are May and June, since they are the mildest ones. You will find the temperatures pleasant. A light long sleeve shirt and pants help shield you from the sun. Always try to bring along an umbrella or raingear, sunscreen and bags to protect your photographic equipment.
Broadly speaking, the days are warm and the nights cold. You have to be prepared for fluctuating temperatures. It would be ideal to bring along a sweater, mittens and a wind-jacket, inside a small backpack. During the day, you can wear long-sleeved cotton shirts and comfortable trousers to move around easily. During the dry season (May-November), the sun forces you to wear sunglasses and a hat, and apply sunscreen.
There is no reason to dress up for dinner at night or on the Hiram Bingham train. A change of clothing is nice but please pack light as you will have to deal with the luggage and staying at different hotels frequently. Since you are traveling by train you are limited to what you can carry onboard. Luggage can be left in Cusco to pick up on your return.
During the rainy season (December- April), it is advisable to bring boots to walk comfortably, since the ground gets too muddy. To protect them from rain, you should also carry your personal belongings and ID in a plastic bag inside the backpack. Be sure you always bring an extra long-sleeved shirt.
Since Machu Picchu has a warm climate, there are plenty of insects and mosquitoes, which mostly appear during sunny days, and whose bites produce skin irritation. We recommend you take insect repellent.
Cusco and the Sacred Valley are also very casual with no formal attire required. If you plan on visiting 5 star restaurants in Lima this is the only reason you may need a jacket and tie for the gentlemen.