Atacama Desert in December

April, May, September, and October offer the sweet spot for Atacama travel—mild days, clear skies, and comfortable sleeping temperatures. During these months, daytime temperatures hover around 70°F while nights drop to a manageable 40°F. The shoulder seasons also mean fewer crowds at popular spots like Valley of the Moon, where sunset tours can pack in 200+ people during peak season. Summer (December through February) brings the desert's brief rainy season, which sounds impossible but actually happens. These summer storms can flood salt flats and make roads impassable, though they also trigger rare wildflower blooms that transform the landscape. Winter (June through August) delivers the clearest skies for stargazing but brutal overnight temperatures that can hit 10°F. Many high-altitude attractions like the Tatio Geysers become even more challenging in winter due to icy conditions. Here's what most guidebooks don't mention: the Atacama's weather can shift dramatically within a single day. I've experienced 60-degree temperature swings between noon and midnight. Pack layers regardless of when you visit, and always bring a warm jacket for evening activities. The dry air means sunburn happens fast—even on cloudy days, the UV radiation at this altitude is intense.