The Yellowstone fires of 1988 collectively formed the largest wildfire in the recorded history of Yellowstone National Park in the United States. Starting as many smaller individual fires, the flames quickly spread out of control due to drought conditions and increasing winds, combining into one large conflagration which burned for several months. The fires almost destroyed two major visitor destinations and, on September 8, 1988, the entire park closed to all non-emergency personnel for the first time in its history. Only the arrival of cool and moist weather in the late autumn brought the fires to an end. A total of 793,880 acres (3,213 km²), or 36 percent of the park, was affected by the wildfires.