The fall rut can make bull elk aggressive toward people and vehicles. Elk damage vehicles every year and occasionally charge visitors. Regulations require staying a minimum of 25 yards away from elk, moose, deer, bison, bighorn sheep, and coyotes.
Also, remember, bears inhabit all of Yellowstone. Hikers should be prepared to encounter a bear at any time. While hiking, it is not unusual to see a bear or encounter a bear at close range.
In the fall, come prepared for a wide range of conditions. Temperatures drop rapidly with shorter days, often falling below freezing overnight. At this time of year, it's a good idea to pack plenty of layers, including insulating items, and both sun and rain protection. Before traveling, check Yellowstone weather forecasts and advisories at Yellowstone's weather page or the National Weather Service.
Rivers and Streams
The Boiling and Firehole Rivers are open for swimming. Remember that rivers and streams in Yellowstone have swiftly flowing currents and always use extra caution around any water.
In the fall, grizzly bears and black bears usually move to higher elevations to feed on whitebark pine seeds, but they are often encountered along roads or hiking trails throughout the park. When hiking or backpacking: travel in groups of three or more, make noise, and be alert for bears.
Other updates: the back northwest corner of Mud Volcano is closed for the season. There is NO LOOP TRAIL past Grizzly Fumarole. Travel to Churning Caldron and Sizzling Basin is discouraged.