Santiago has a semi-arid climate with mild winter and dry summers. The Andes Mountains receives ample of snowfall during winters to cater to skiers and snow lovers. However, the city is subjected to temperature inversions and many a times the winter air is considered unhealthy due to the smog.
Throughout the year, the temperatures can slide through a big range which is typical to the region.
Summer: December to March is summer season with an average temperature of around 25 degrees Celsius or cooler. However, the temperature can touch as high as around 36 degrees Celsius! The night usually much colder.
Autumn: April to May is autumn season (sometimes autumn can pre-set in March) with an average temperature of around 20-22 degrees Celsius and it can get cooler- touching to around 10 degrees Celsius.
Winter: June to August is winter season with temperature being well below 10 degrees Celsius and barely touching freezing temperatures. However, winters do give rise to lot of smog effect due to temperature inversion.
Spring: September to November is the spring season with pleasant weather which can range from a slow as 6 to as high as 23 degrees Celsius.
Rain: The rainy season intermingles partly with autumn and partly with winter with a peak season during June-July.
The best time to visit Santiago is during autumn and spring.