Santiago has a somewhat cooler Mediterranean climate: relatively hot dry summers (November to March) with temperatures reaching up to 35 degrees Celsius (95 degrees Fahrenheit) on the hottest days; winters (June to August) are more humid with cold mornings, typical maximum daily temperatures of 13 degrees Celsius (56 degrees Fahrenheit), and minimums of a few degrees above freezing. Occasional snowfall occurs in the city, and may extend throughout the city, though this happens infrequently (about every 8–10 years). Mean rainfall is 360 mm per year and is heavily concentrated in the cooler months.
The climate of Santiago is a warm-temperate climate with winter rainfall and prolonged dry season, better known as continental Mediterranean climate.
Within the main climatic characteristics of Santiago is the concentration of about 80% of rainfall during the austral winter months (May to September), varying between 50 and 80 mm of rain fall during these months. That amount contrasts with figures for the months corresponding to a very dry season, caused by an anticyclonic dominance continued for about seven or eight months, mainly during the summer months between December and March. This season, the water drop does not exceed 4 mm on average. These rains are usually composed only of rain, as the snowfall and hail is produced mainly in the sectors of the Precordillera about 1500 meters, in some cases, nevazones affect the city but only on its eastern sectors, where in very rare opportunity extended to the rest of the city.
The temperatures vary throughout the year from an average of 20 °C (68 °F) in January to 8 °C (46 °F) in June and July. In the summer, January is hot, easily reaching over 30 °C (86 °F) and a record high close to 37 °C (99 °F), while nights are generally pleasant and slightly cooler without lowering of 15 °C (59 °F). For his part, during autumn and winter the temperature drops and is slightly lower than the 10 °C (50 °F), the temperature may even drop slightly from 0 °C (32 °F), especially during the morning, and its historic low of ?6.8 °C (20 °F) in 1976.
Santiago's location within a watershed is one of the most important factors in the climate of the city. The coastal mountain range serves as a "screen climate" to oppose the spread of marine influence, contributing to the increase in annual and daily thermal oscillation (the difference between the maximum and minimum daily temperatures can reach 14°C) and maintaining low relative humidity close to an annual average of 70%. It also prevents the entry of air masses with the exception of some coastal low clouds that penetrate to the basin through the river valleys.
Prevailing winds are from the southwest direction, with an average of 15 km / h, especially during the summer as in winter calm prevail.
(Source: Wikipedia, Weather Agency of Chile)