"Mount Baker dominates the skyline from Bellingham, Washington, and Vancouver, British Columbia. On cold, clear winter days, dramatic increases in the steam plume rising continuously from Sherman Crater can alarm local residents. This apparent increase in plume vigor occurs because of condensation of steam in cold, calm air. In 1975, however, increased steaming and melting of snow and ice around Sherman Crater did signify a change in heat output from the volcano's interior. Although the increased heat flow gradually subsided, it could have signaled the start of eruptive activity, and precautions were wisely undertaken. So that the public can be warned of, and be prepared for, future eruptions and other hazardous events at Mount Baker, U.S. Geological Survey (USGS) scientists are studying the volcano's past behavior and monitoring its current activity."
U.S. Geological Survey: http://www.usgs.gov/