South Cascade Glacier is a large alpine glacier in the North Cascades of Washington, USA. It is bordered on the east by 8,261-foot (2,518 m) Sentinel Peak, and is about 17 mi (27 km) north of Glacier Peak in the Glacier Peak Wilderness. Meltwater from the glacier flows directly into South Cascade Lake, which feeds the South Fork Cascade River, which is a tributary of the Skagit River.
The South Cascade Glacier has been closely monitored by glaciologists studying the effects of climate on glaciers. Between 1958 and 2009 South Cascade Glacier lost nearly a half of its volume.