The best time to visit Peru is during the dry season, between May and October, which sees sunny days, bright blue skies in the Andes, and chilly nights. It is a wonderful time to be in Peru, especially if you plan to go on a trek, but being the peak season, early booking is crucial.
Visitors will notice more rain between November and April, with the wettest months being January and February. Travel at this time does offer the advantage of fewer visitors, greener scenery, and some lower rates for flights and hotels.
The Amazon also experiences more rain between November and March, but this should not deter you from visiting — the flora and fauna will still be abundant and there are always breaks in showers.
From December to April summertime, temperatures from 25° to 35° C; hot and dry. There are the best months for swimming. Wintertime, May - November; the temperature drops a bit and it is cloudy. On the coast, the climate is determined by cold sea-water adjoining deserts: prevailing onshore winds pick up so little moisture over the cold Peruvian current that only from May to November does it condense.
The resultant blanket of cloud and sea-mist extends from the south to about 200 km north of Lima, This garua dampens isolated coastal zones of vegetation (called Lomas) and they are grazed by livestock driven down from the mountains. During the garua season, only the northern beaches near Tumbes are warm enough for pleasant swimming.
From April to October is the dry season. hot and day during the day, around 20° - 25° C, cold and dry at night, often below freezing. From November to April is the wet season, dry and clear most mornings, with some rainfall in the afternoon, with a small temperature drop (18° C) and not much difference at night (15° C).
Peru's high season is from Jun to August, which is the best time for hiking the Inca Trail or trekking and climbing elsewhere in the country. At this time the days are generally clear and sunny, though nights can be very cold at high altitudes. The highlands can be visited at other times of the year, though during the wettest months from November to April some roads become impassable and hiking trails can be very muddy.
April - October, dry season, temperature up to 35° C. This is the best time to visit the jungle. In the jungle areas of the south, a cold front can pass through at night. November - April, wet season, heavy rainfall at any time, humid and hot. During the wet season, it only rains for a few hours at a time, which is not enough to spoil your trip, but enough to make some roads virtually impassable.