Despite occasional rainy days, April to May and September to October are deemed to be the best time to visit Machu Picchu. These are the periods when the weather is pleasant, the crowds are thinner, and the events like Warachikuy occur. June through August, a peak of the dry season, sees the surge of tourism and inflated room rates, but if that doesn't bother you, why not experiencing all those amazing trails and marvelling at how the salt is harvested at Salinas de Maras? Low season from November to March is famous for rain downpours, peaking in February and causing closures of the Inca Trail. If you are a real dare-devil, don't shy away from bright Cusco Christmas celebrations and Cusco Carnival during winter.