While it is true that the weather of Cusco varies throughout the year according to seasonal changes, it is also true that there are two constant situations that remain from January to December: if you are under the sun, you will be hot—usually during the day—, and if you are in the shade, you will be cold—on cloudy days and during the night.
Having said that, and to be more specific, the weather in Cusco and the weather in Machu Picchu are characterized by two seasons: rainy season (December - April) and dry season (May - November).
During the day
During the night
Waterproof clothing
Umbrella
Closed and resistant footwear
During the day
During the night
Warm clothing
Water
Insect repellent
Lenses with UV protection
Sunblock
Remember to also be prepared for altitude sickness or also known as "soroche". Machu Picchu is a high altitude area. If you want to know more about this topic, we invite you to read our section "Altitude in Machu Picchu".