I found this on a website ASp...

Largely nomadic, northern hawk owls move across their range in response to prey availability and climatic conditions. When the weather is severe and prey availability is low, northern hawk owls may move southward towards the more temperate latitudes of Alaska, Canada and the northern continental United States. These southern movements are referred to as "irruptions" and may span thousands of miles.


So your town has been the fortunate victim of an irruption.