Summer : In San Pedro, the high season begins in November and lasts until March, largely coinciding with the summer season in the Southern Hemisphere, making it a very hot time. During this period, temperatures can range from as low as -10°C in the El Tatio geothermal field to around 32°C in the Valle de la Luna (Valley of the Moon).
It should also be considered that it is the Bolivian highland winter season or rainy season, which occurs mainly during the month of February.
The peak of the "highland winter" begins in early February. In the rainiest years, which occur every seven years, the rains start daily between 3 and 4 p.m. and, depending on the intensity, can last between three and five hours or more. When this persists for one or more weeks with moderate to high intensity, it causes roads and tours to be closed, sometimes for up to three weeks.
Autumn: With the arrival of autumn, the extreme daytime heat begins to subside, and tourism in San Pedro de Atacama starts to decrease. The temperature of the lagoons in the salt flats also drops slightly, so if you're hoping to swim but aren't used to the cold, this might be something to consider. During this time, tourist sites are less crowded, and the destination generally has a more tranquil atmosphere, which may be interrupted by the occasional holiday.
Winter : During July and August, there is a surge in tourism due to vacations in the Northern Hemisphere. For those hoping to take an astronomical tour, it's the best time to see the center of the Milky Way, Sagittarius A*. Daytime temperatures in San Pedro are pleasant, although the days are shorter during the winter, and therefore most tour operators shorten their tours by about an hour.
Depending on the winter, temperatures start to drop to a minimum of -5°C in the town, and in the Tatio geysers during the coldest winters it can drop to -20°C, so bringing thermal clothing and several layers is essential if you want to get out of the vehicle and do the walks in the highlands.
During the winter, high-altitude tours may be sporadically interrupted when there is a blizzard, which does not mean that tours at lower altitudes will stop operating.
Spring: Spring is the dry season in San Pedro, characterized by stable weather and a gradual increase in temperatures. During the last weeks of September and the first weeks of October, the galactic center begins to disappear. It generally doesn't rain at all, and the probability of a tour being canceled in spring is practically nonexistent.
