San Pedro de Atacama has a cold desert climate and experiences extremely dry weather with little or no rainfall and temperatures averaging around 77°F to 86°F (25°C - 30°C) in the summer months from December to January. During the winter months, from June to August, the temperature averages drop to 64°F to 77°F (18°C - 25°C) during the day, while average night-time temperatures in winter drop to below zero and can even reach as low as 14°F (-10°C). Some visitors experience altitude sickness and travellers should take this into account. Altitude sickness can manifest as dizziness, lethargy or headaches. If you have any respiratory problems then travel in this area may be difficult for you due to the altitude. The weather in San Pedro de Atacama is ultimately quite pleasant all year, considering that it is located in a desert, and there isn't really a peak tourist season or an ideal time to visit. The season of your stay should be determined by the activities you want to try.