Hail — Missoula, Montana

2025-07-31 · near Grass Vly, Missoula, Montana

Event narrative

A slow-moving thunderstorm impacted the area northwest of Missoula, producing both large hail and heavy, localized rainfall. Quarter-sized (1.00 inch) hail was estimated via photos near the Frenchtown Mill. The storm's torrential downpour resulted in an official measurement of 0.92 inches at the Missoula International Airport (KMSO), with radar estimating up to 1.40 inches nearby. This intense rainfall overwhelmed drainage systems on Broadway, causing water to flood the eastbound lane. A downed tree was reported on the northbound lane of Highway 83 near milepost 31, north of Summit Lake.

Wider weather episode

Slow-moving thunderstorms, enhanced by anomalously high atmospheric moisture, brought periods of heavy rain and large hail to portions of west-central and southwest Montana.

View location on OpenStreetMap → (46.9744, -114.2108)

Source: NOAA Storm Events Database, event_id 1286108. Narrative written by the NWS forecast office that issued the report.