California depends on snow and ice in the Sierra Nevada mountains to provide water during the dry summer months. However, with climate change, this natural water source is shrinking. Warmer temperatures are reducing snowfall and causing glaciers to melt more quickly. At the same time, wildfires in the region are becoming more frequent and intense. These fires darken snow and ice surfaces with ash, which can make them melt even faster. This study focuses on the San Joaquin watershed—a major river system in California—and examines how warming temperatures and wildfires are affecting glaciers and snowpack over time. Using satellite images and historical fire data, we measured how much glaciers have shrunk, how snow patterns have changed, and where wildfires have occurred. Our results show that wildfires and warming are closely linked to the loss of snow and ice in this region. This could have serious consequences for California’s water supply, especially during hot, dry summers. By better understanding how glaciers and snow respond to both climate change and wildfires, this research can help scientists and water managers prepare for future challenges in mountain water systems.