In this Deep Dive, we head to the Sierra de San Pedro Mártir, near Ensenada—where snow has arrived a full month early. Officially confirmed by CONAGUA on November 19, this event transforms one of Mexico’s highest peaks into a surreal blend of winter wilderness and world-class science. Home to the National Astronomical Observatory, the Sierra’s clear, icy air allows astronomers to see deep into space while hikers and park rangers face black ice, freezing fog, and road closures. As Baja braces for an early winter, this story asks: what happens when climate, ecology, and astronomy all collide on the same mountain? 🌨️🔭🌎