Peru’s climate has two main seasons – wet and dry – though the weather varies greatly depending on the geographical region. Temperature is mostly influenced by elevation: the higher you climb, the cooler it becomes.
The peak tourist season is from June to August, which coincides with the cooler dry season in the Andean highlands and summer vacation in North America and Europe. This is the best (and busiest) time to go trekking on the Inca Trail to Machu Picchu, or climbing, hiking and mountain biking elsewhere.
People can and do visit the highlands year-round, though the wettest months of December to March make it a wet and muddy proposition. Many of the major fiestas, such as La Virgen de la Candelaria, Carnaval and Semana Santa, occur in the wettest months and continue undiminished even during heavy rainstorms.On the arid coast, Peruvians visit the beaches during the most hot and humid time of the year, from late December through March. In central and southern Peru, the coast is cloaked in garúa (coastal fog) for the rest of the year. Although the southern beaches are deserted then, the coastal cities can be visited at any time. In the north, the coast usually sees more sun, so beach lovers can hang out there year-round.In the eastern rainforest, of course, it rains. The wettest months are December through May, but even then it rarely rains for more than a few hours at a time, so there’s still plenty of sunshine to enjoy. Follow the locals’ example: briefly take cover during the heaviest downpours. It’s not a big deal.