During the summertime from December to March (usually extending into April) the temperature rises to a range between 20C to 35C in the Coast, being warm and dry with almost no rain. However, this is the rainy season in the highlands producing a rise in the rivers that flow into the coast. During this season, the temperature in the mountains is warm during the day and cold during the night. In the Jungle it becomes humid and hot with heavy rain fall.

During wintertime, from May into November, the temperature in the Coast drops to a range between 10C to 20C with a blanket of clouds and sea mist and very humid. This is the dry season in the mountains with little rain fall, lots of sunshine during the day and colder temperatures during the night (usually below freezing).

The weather in Peru may be dramatically altered by the "El Niño" , a warming of the waters of the eastern Pacific which appears every 5-7 years during the summertime and causes a dramatic increase of the temperature, very heavy rains and mud slides in the mountains and floods along the Coast (mainly in the North).