<p>Wildfires in the Arctic are accelerating ecosystem damage and increasing global carbon emissions. Siberia, a major Arctic wildfire hotspot, is shaped by both local weather and distant climate influences. Here we use climate reanalysis data and numerical model experiments to show that summer wildfires in Siberia are strongly influenced by rainfall patterns over the Tibetan Plateau, one of the Northern Hemisphere’s largest summer heat sources. A dipole in Tibetan Plateau rainfall—wetter in the west, drier in the east—coincides with more fires in central Siberia and fewer in the east. This pattern alters high-altitude winds, shifting the jet stream northward and generating air flow changes that create favorable fire conditions across Siberia. Model experiments support a causal link. The resulting carbon dioxide emissions can match annual emissions from all Nordic countries. These findings highlight an overlooked driver of Arctic wildfires and improve our understanding of their role in the global carbon cycle.</p>