A rare weather phenomenon has caused clouds to form over the Grand Canyon.

Visitors gathered at Arizona's Grand Canyon National Park on Thursday to see the white blanket of clouds resting just below the canyon's rim.

The weather event, which happens once every few years, came in the aftermath of recent rain in northern Arizona that left heavy fog, Cory Mottice, from the National Weather Service, explained to the Associated Press.

A lack of wind helped the fog accumulate in the Grand Canyon overnight and was then trapped there due to warm air, Mottice said.

The clouds should clear up within a few days, he told the AP. Though the event is rare, the last time it happened at the national landmark was in 2013.

The Grand Canyon National Park posted a time-lapse video of the clouds on Facebook. Check it out below.