Frost/Freeze in Missoula / Bitterroot Valleys, Montana

The Ravalli County Airport recorded a low of 21 degrees, while a National Weather Service employees observation in the Ranch Club area recorded 22 degrees. On May 19, lows ranged from 30 to 33 degrees. Orchards in the Bitterroot Valley reported that approximately one-third of their apple crops did not fruit due to the combination of an early warm winter, early budding, and these May freezes.

An unseasonably cold upper-level trough, originally an Aleutian Low/Gulf of Alaska low, was dislodged and sagged south over the Pacific Northwest and Northern Rockies. This system brought a prolonged period of late-season winter weather, including persistent graupel showers, accumulating mountain snow, and record or near-record cold temperatures leading to widespread frost and hard freezes across Western Montana.