Climate Peru
Peru has a varied climate. The coasts bordering the Pacific (la costa) have a mild, dry climate, influenced by the cold Humboldt current. Lima and the surrounding area experience wet winters, but are bathed in sunshine in summer. It's cold in the Andes (the sierra) due to the altitude. Daytime temperatures are pleasant, but nights are cold. The climate is generally dry. In the eastern zone, the selva, the climate is humid equatorial, and rainfall is more frequent, but occasional outside the rainy season. One important thing to remember: when it's winter, Peru isn't necessarily summer, even though it's in the southern hemisphere. From December to April, it's summer in Lima and on the coast, but both the sierra and the selva experience significant rainfall. The best climatic period is between April and December.
Softness and mist on the coast
Situated between sea level and an altitude of 500 m, the costa, although very close to the equator, has an average annual temperature of 18°C. This is due to the proximity of the cold Humboldt current, which sweeps along almost the entire coastline, creating a permanent haze that prevents rainfall (less than 100 mm of precipitation annually), making it extremely dry despite humidity levels of around 80%. From May to October, clouds cover the coast up to an altitude of 600 m, above which the temperature becomes milder and the sun more present.
In the north, the beaches are sunny, with an average temperature of 25°C. After Chiclayo, the climate becomes decidedly hot. In summer (December to March), when the fog lifts, the heat is truly overwhelming. The vegetation becomes increasingly dense as you approach the border with Ecuador.
Humboldt Current and Niño Costero
Every 5 years or so, El Niño makes its appearance on the Peruvian coast, and this warm current is a real disaster for the Ballestas Islands and the Paracas reserve. It's the cold Humboldt current that maintains the ocean's rich plankton content, the staple diet of seals, sea lions, penguins, dolphins and birds. El Niño, which is too warm, drives plankton away, forcing animals and birds to migrate in search of new food. Sometimes, El Niño is just a few degrees warmer, which is quite pleasant in the Pacific, although it throws the food chain out of balance.
At other times, El Niño gains in strength, triggering flooding phenomena that ultimately have consequences just as far-reaching as earthquakes. Between December 2016 and March 2017, this climatic phenomenon shocked the entire country and severely affected the entire northern coastal region: Chimbote, Trujillo, Chiclayo, Piura, Tumbes and the surrounding countryside. Heavy mudslides also affected the regions near Lima. A severe drought and several forest fires preceded the storm, before the warming of the Pacific waters triggered unprecedented rainfall. The dried-up rivers around which precarious housing had been built filled with water in a matter of hours. The toll was heavy: over 1 million people affected, 231,874 stricken and 143 dead. El Niño is a recurring phenomenon. Two major episodes in 1982-83 and 1997-98 claimed more victims. The challenge remains to take the necessary preventive measures, such as enforcing no-build zones and setting up effective river drainage systems. Unfortunately, public corruption often gets bogged down, with emergency rebuilding taking place in the same disaster areas.
Sun and cold nights in the sierra
Between 2,500 and 3,500 m altitude, the climate is temperate, but the temperature varies greatly between day and night. This is the case, for example, in Arequipa or in the Sacred Valley of the Incas, at a lower altitude than Cusco. The sky is often a deep, clear blue, which, thanks to its proximity to the Equator, makes for a comfortable feeling of warmth. But beware of the sun's rays. At night, however, hats and ponchos are the order of the day, as temperatures drop considerably. There is very little heating in rural homes, and even in standard hotels, which sometimes supply electric auxiliary models. In the countryside, people gather round and sometimes sleep by the stove when the nights get too cold.
The higher you go, the lower the temperature and, above 4,800 m, there are no settlements except for those linked to mining (Cerro de Pasco and La Oroya). On the Altiplano, in the Puno region, at an altitude of 4,000 m, the annual temperature is cold, averaging 3 to 8°C with frosts in the wet season (November to May), and 10°C in the dry season. A drop in temperature can also be cruelly felt at night during the "las heladas" period between June and July.
Beware of the rainy season in the sierra, from mid-December to around mid-March, which often causes landslides. The rains are episodic and heavy, and the roads built into the mountainsides are friable, often resulting in roads being cut off, making certain regions or places inaccessible for several hours or days. In such cases, there's no choice but to be patient and wait for someone to come and clear the way. Even Machu Picchu is not spared from mudflows, known here as "huaicos", so this is not the best time to travel.
Heat and humidity in the selva
In the high selva, the average temperature fluctuates between 22 and 26°C, decreasing with altitude. Particularly intense rainfall occurs between December and April, causing landslides. Surprisingly, Machu Picchu is almost more Amazonian than Andean, situated on the border between the two geographic regions. The weather at the archaeological site is therefore often quite fine, but it is also rainy and subject to fog, which does nothing to detract from its mystique. The Kuélap ruins in northern Peru share the same geographical characteristics. The rest of the year, from May to November, the climate is generally dry and hot. This becomes increasingly true as you leave the Andes behind and approach the Amazon plain.
In the lower selva, the average temperature is 31°C, but you can feel hotter because of the humidity that sticks to your skin and envelops you. The deforested towns (Iquitos, Pucallpa, Puerto Maldonado) are much hotter and feel much hotter than the forest itself. At certain times of the day, no one goes out and fans are running everywhere. In the heart of the forest, the humidity is high, but the heat remains bearable. It rains less than in the high selva, but humidity is high and thunderstorms frequent. You can visit the region during the rainy season, but we wouldn't recommend it, as the animals are nowhere to be seen. On the other hand, navigating Iquitos, for example, which is partly submerged, can have its charm.
