Peru has three radically different climate zones: a near-rainless coastal desert (15–28°C), the Andean highlands ranging from below freezing to 20°C depending on altitude, and a hot, humid Amazon jungle (25–35°C year-round). The best time to visit Machu Picchu, Cusco and the Andes is the dry season from May to September. Few countries pack such extremes into so little space, and understanding these zones is the key to packing and planning a trip.
Why Peru Has Three Climates at Once
Peru's geography forces three climate worlds into a country roughly the size of Alaska. Running parallel to the Pacific is a thin coastal desert, behind it rise the Andes — the second-highest mountain range on Earth — and beyond them spreads the western Amazon basin, the largest rainforest in the world. Because temperature and rainfall here are governed more by altitude and ocean currents than by latitude, the weather can change completely over a short distance.
The single biggest driver on the coast is the cold Humboldt Current, which sweeps north from Antarctica. It chills the air over the Pacific, suppresses evaporation and rainfall, and creates the persistent grey fog Limeños call garúa. The result is one of the planet's driest inhabited coastlines sitting just a few degrees south of the equator, where you would normally expect tropical heat.
The Coast: A Foggy Desert by the Sea
Lima averages about 19°C (66°F) year-round but receives under 10 mm of rain annually, making it one of the driest major cities on Earth — second only to Cairo in desert-city size. From May to November a thick marine fog layer hangs over the city, keeping it cool, damp and overcast even though almost no rain falls. From December to March the fog lifts and summer arrives, with sunshine and temperatures of 25–28°C.
Don't expect warm swimming, though. The Humboldt Current keeps coastal waters around 15–18°C, cold enough that Humboldt penguins live on islands near the equator. Rare El Niño events — a phenomenon first named by Peruvian fishermen — can reverse this pattern, bringing destructive downpours to the normally bone-dry coast.
The Andes: Two Seasons, Big Daily Swings
The highlands run on altitude, not calendar months. Cusco, at 3,400 m, sees daytime highs around 20°C but cold nights, with a daily temperature swing that can exceed 15°C — warm in the sun, chilly the moment it sets. Higher still, the altiplano above 4,000 m near Lake Titicaca can drop to -10°C on winter nights.
The Andes have two clear seasons rather than four:
- Dry season (May–September): clear skies, sunny days, cold nights, and the best mountain visibility.
- Wet season (October–April): afternoon thunderstorms, muddy trails and obscured views.
Cusco receives around 700 mm of rain a year, almost all of it between October and March. The famous Inca Trail to Machu Picchu closes every February for maintenance during the heaviest rains, so that month is off-limits for trekkers.
The Amazon: Hot and Wet All Year
East of the Andes, the rainforest stays consistently hot and humid, with temperatures of 25–35°C in every season. Iquitos, the largest city reachable only by river or air, records around 2,800 mm of rain annually — roughly 300 times what Lima receives. There is no truly dry month, only "drier" and "wetter" ones.
The wettest stretch runs from December to May, when rivers can rise by more than 10 metres, flooding the forest and opening up channels for canoe exploration and different wildlife viewing. The drier months of June to October bring lower water, more exposed trails and easier jungle trekking. The transition from coastal desert to Amazon jungle can happen across just 200 km horizontally — but with more than 4,000 m of elevation change in between, one of the most compressed climate gradients anywhere on Earth.
When to Go: Best Time to Visit Peru
For most travellers, May to September is the ideal window. It is the Andean dry season, delivering clear skies over Machu Picchu, comfortable daytime temperatures and reliable trekking. It is also peak season, so book accommodation and the Inca Trail months in advance. A quick guide by region:
- Machu Picchu, Cusco & Lake Titicaca: May–September (dry, clear).
- Lima and the coast: December–March (the fog lifts, bringing summer sun).
- Amazon jungle: June–October for easier trekking; wet season for higher rivers and boat access.
Because a single trip often combines all three zones, smart packing means sunscreen for the coast, warm layers for the highlands and rain gear for the jungle — sometimes used on the same day. For more on the country's regions and travel basics, see our peru country guide.
Frequently Asked Questions
What is the best month to visit Machu Picchu?
The driest, clearest months are June, July and August. They offer the best visibility and lowest rain risk, but also the largest crowds. May and September are excellent shoulder months with good weather and fewer visitors.
Why is Lima so cloudy if it almost never rains?
The cold Humboldt Current chills the air over the Pacific, condensing it into a low marine fog (garúa) that blankets Lima from roughly May to November. The fog cools and dampens the city without producing meaningful rainfall.
Does it ever rain on Peru's coast?
Very rarely. Some desert areas can go years with no measurable rain. The major exception is an El Niño event, which can warm coastal waters and trigger heavy, sometimes catastrophic, downpours.
How cold does it get in the Peruvian Andes?
It depends on altitude. Cusco nights hover near freezing in the dry season, while the high altiplano above 4,000 m can fall to around -10°C on clear winter nights, even though daytime sun feels warm.