Peru is a very diverse country. The coast, the mountains and the jungle don’t have the same weather. I have some friends that never imagined this and when then came, they had to buy some clothes. Shorts and T Shirts weren’t enough warm in Cusco, especially in the night. So, the best time to visit Peru, depends on what part of the country you are interested in.
In all cases, I recommend you to always check the weather forecast.
The Peruvian coast
On the coast, the summer months are from December to April.
I met some visitors that came to Lima in July and were very surprised to see the iconic (for locals) cloudy sky, as we call it ” Lima panza de burro” (Lima donkey’s belly)
Between july and september is the winter on the peruvian cost, nothing extreme , 11º/ 50 °F is the minimum temperature.
Only the northern beaches such as Mancora, Punta Sal, Vichayito are warm the whole year.
Best months to visit the peruvian mountains
On the mountains, the dry season is from May to September. It is the best time to visit Peru for trekkings, especially in Cusco, Arequipa and Caraz. The wet season is between October- April. Even if you are coming on the dry season, you should bring a rain proof jacket, weather in the Andes can be changeable. So is it only possible to go hikings/trekkings on the dry season? No, Trekking is possible at other times of the year but conditions are less pleasant. I hiked some trails in Cusco on December and I must say the mud in the shoes and the cloudy landscape were things that I could absolutely skip.
The Peruvian jungle
The mountains and the jungle have a similar calendar- time. Keep in mind, in the jungle it always rains, the difference is the intensity and the duration. Between October and March it could rain for many days non-stop.
If you want to know 10 travel tips before visiting Peru, check this article.