The owls are known to head south in large numbers every few years in what are known as irruptions.
But the number seen this winter is far greater than ever before.
“What we're seeing now -- it's unbelievable," said Denver Holt, head of the Owl Research Institute in Montana during an interview with Reuters.
“One showed up at the airport in Hawaii (for the first time on record), and they shot it,” he added.
Holt and other owl experts say an overabundance of lemmings, which the owls feed on, resulted in an owl population boom. Each breeding pair hatched as many as seven chicks.
More birds and less food this winter at high North American latitudes may have driven many of the owls much farther south in search of food.