Glaciation has affected the shape of mountain ranges and has induced a global increase in erosion rates during the past 2 m.y. The observed increase in erosion rates appears to vary with latitude, reaching a maximum at mid-latitudes that is particularly well defined in the Southern Hemisphere. Although it is likely that climate played an important role, the processes responsible for such latitudinal distribution of erosion are unclear. Here we exploit the meridional extent of the Patagonian Andes and identify an erosion hotspot at ∼44°S. Using a glacial erosion model and formally inverting the available thermochronometric and geobarometric data, we show that this hotspot coincides with the location of maximum precipitation that follows the Southern Hemisphere Westerlies during glacial periods. We propose that the increased precipitation rates at ∼44°S led to greater ice sliding velocities and faster glacial erosion. Our results imply that the migration of the westerly wind belt toward the equator since 2–3 Ma may have played an important role in determining the distribution of mountain erosion in the Southern Hemisphere.