Above-average temperatures mean grizzly bears have started to emerge from hibernation in Yellowstone National Park. Over the last five years grizzlies have tended to emerge during the first half of March, which puts Monday’s first sighting of activity 2-4 weeks sooner than usual.

Yellowstone spokesman Al Nash says that could be a problem for visitors who are more used to preparing for potential grizzly encounters in the warm summer months.

"You may not immediately think about the need to encounter a bear when the temperature is 30, 40, 50 degrees colder and there’s snow on the ground," he says.

Nash recommends hiking in groups, carrying bear spray, and making noise when approaching blind corners.

Since bears are hungrier and potentially more aggressive during this time, certain bear management areas of the park will be closing in order to minimize the risk of human-bear encounters.