The climate in Lima is relatively mild, even though being located in the Tropics. The average temperatures range from 14°C to 20°C (low) and 25°C to 32°C (high). Relative humidity is very high, and produces passing morning fog from December to June and persistent low clouds from May to November. Sunny, moist and warm summers (December - April) are followed by cloudy, damp and cool winters (June - October).

Rainfall is almost unknown. The yearly average of 7 mm reported at the airport is the lowest of any large metropolitan area in the world. Summer rain occurs in the form of isolated light and brief afternoon or evening events. The peak of the 'rainy season' - this term really does not apply - occurs during winter when night / morning drizzle (called 'garúa'), become more frequent.

One thing to take into consideration is that because of the coast, hills and valleys, there is no general climate for Lima. You will find a big difference in climate between the districts directly on the coast and those that are further away east. For example, in winter areas like Miraflores, San Isidro, Barranco and Chorillos but as well parts of Surco will be cool, damp and foggy as they are close to the ocean. Going east away from the sea you will notice step by step a change in climate and weather.

Districts like Lima Downtown, San Borja and Monterrico (Surco) have already much better weather. When going a little bit further east to La Molina and La Planicie the climate will be much warmer and drier and you will see more sun especially in winter. The Cieneguilla area even further east provides sunshine and spring-like weather throughout the year.

Lima is best described as having micro-climates; while winter is generally winter in all of Lima, a 30 minute drive in any direction can put you in a warmer, colder, drier or wetter area depending on your elevation and distance to the coast. Looking at Peru, you'll have 'winter' at the coast and 'summer' in the highlands and the Amazon basin or vice versa.

Mainly responsible for the extremely different weather conditions is the Humboldt Current, a cold ocean current that extends along the West Coast of South America from Northern Peru to the southern tip of Chile. Air is cooled by the current and thus is not conducive to generate rain (although clouds and fog are produced).

Water temperatures are generally low (between 13 to 14º C in winter and 15 to 17º C in summer) and swimming is really ‘refreshing’…

The Humboldt Current was named after Alexander von Humboldt and is one of the major up welling systems of the world, supporting an extraordinary richness of marine life. The Peruvian coast is one of the richest areas of the world in terms of biomass and diversity.

Don’t think that because you are visiting a country in the tropics, that it doesn’t get cold. In the winter months you’ll need sweaters, thick socks and a good blanket at night. With the temperature changes day/night and the high humidity, you can catch a flu rapidly. If you arrive in summer, it'll be your best choice to bring light clothing.