Updated 2:25pm:

A dense smoke advisory is in effect for until 5pm Thursday for the greater Lake Tahoe area and the Carson Valley.

The National Weather Service in Reno is discouraging people in the basin, Alpine, Douglas and northern Mono counties from outdoor activities. Visibility is expected to be less than 3 miles and the air quality is expected to get worse as the day goes on.

Lake Tahoe Unified School District officials are monitoring the air throughout the day to determine if students, who returned to school on Monday, should be outside for recess and if athletes should be practicing outdoors.

The heavy smoke is coming from the Rim Fire, which is burning near Yosemite National Park. It has burned 179,481 acres and is 20 percent contained. It is the largest fire on record to burn in the Sierra Nevada and the sixth largest in California’s history. At least two dozen structures have been destroyed. The reservoir that provides drinking water for San Francisco remains in jeopardy.

The American Fire burning near Foresthill is almost fully contained. Full containment is expected Thursday – three days sooner than originally predicted.

— Lake Tahoe News staff report