The chinook is a warm, dry wind that sometimes blows into parts of the United States.
On January 22, 1943, such a wind brought an early spring to the residents of the Black
Hills of South Dakota. In the town of Spearfish, temperatures shot up forty-nine degrees
in only two minutes, a too-rapid change that caused glass windows everywhere to crack.
However, the wind did not affect all parts of the towns in the area. In the town of
Lead, the temperature was measured at 52 degrees, while only three miles away in
Deadwood, it was -16 degrees. Spearfish’s temperature continued to jump around crazily.
An hour and a half after the initial temperature change, the thermometers again read
four degrees below zero. In other towns, it alternated between nine and fifty degrees
Chinooks are winds formed when bodies of humid air cross the Rocky Mountains in the
mid-western United States. The rising humid air releases moisture as rain or snow, a
process that creates heat and stops it from cooling. This newly dried breeze moves
quickly down the mountainsides, warming rapidly to high temperatures. The Plains Indians
called this wind the “chinook,” or the “snow eater.”
The rapid fluctuations in the Black Hills area of South Dakota was caused by the bumpy,
uneven landscape of the area. The hills created ripples in the wind’s flow, making it
dip down into certain areas while avoiding others.