Tornado Risk in Yellowstone County, MT
Yellowstone County, MT: what NOAA's tornado record says
21 tornado tracks have crossed Yellowstone County since 1955 by NOAA's count, roughly one every 3.6 years - the Moderate band on this site's scale. That is the 53rd percentile nationally for tornado frequency. Montana has 56 counties in this dataset; Yellowstone County ranks 3 of them by frequency.
The number that matters more than frequency
No violent (EF4-5) tornado has been recorded in Yellowstone County in NOAA's 76-year database. Of its 21 recorded tracks, 18 were weak (EF0-1) and 3 significant (EF2-3).
Shelter and safe-room economics
Montana does not currently have a confirmed state rebate layered on top of FEMA's 75% Hazard Mitigation cost-share, so a Yellowstone County homeowner should expect the full national range: $2,890-$13,280, $7,645 typical.
Power after the storm, not just shelter during it
171,583 people live in Yellowstone County, and a tornado outbreak's power loss usually reaches far more of Montana than the tracks themselves touch. A portable battery unit is the faster, no-fuel way to bridge that outage.
What Yellowstone County's figure does not tell you
Yellowstone County's figure is county-wide, not address-specific. Yellowstone County covers about 2,633 square miles, so a single touch here counts the same as a single touch in a county a fraction of that size. NOAA also documents that older records undercount weaker tornadoes from before Doppler radar became standard. Yellowstone County has about 171,583 residents.