Uyuni weather in December

Uyuni's forum is clear that by May the famous mirror effect on the salt flats is no longer reliable - that's really a December-through-March phenomenon, and much of the salar has dried out by this point, though a lucky visitor might still catch some water in patches. A rain jacket becomes unnecessary this time of year, but nights turn genuinely brutal - one traveler reported around -10C at 4,400m elevation. The honest framing from regulars: come for the dry, otherworldly salt-flat scenery and star-filled skies, not for a shot at the reflection photos, and pack serious cold-weather gear regardless of how warm the days feel.

Forum posters give genuinely mixed advice on November - some call it a good window since the rains typically haven't started yet, meaning full access to sights like Fish Island (Isla Incahuasi) and an overnight stay at a salt hostel that become impossible once the salt flat floods; others frame November as already rainy-season-adjacent, with a real risk of transport disruption especially in the surrounding highlands. Posters are consistent that the classic mirror-reflection photos require standing water on the salt, which typically doesn't happen until the wetter February-March window - so November visitors should expect the dry, cracked salt-flat look rather than the famous reflection shots. Nights are described as genuinely freezing regardless of the exact date, with extra blankets provided at accommodations and posters confirming a sleeping bag generally isn't necessary given that provision.