Flash Flood — San Juan, Utah

2025-08-26 · near Mexican Hat, San Juan, Utah

Event narrative

At approximately 5:20 PM MDT, heavy rain in the area north of Mexican Hat, UT, resulting in failed culverts and flash flooding. On State Highway 163, the failed culverts and and heavy rain resulted in water over the road, making them impassable until the water receded. Additionally, heavy rain in this region led to water over the road on County Highway 261, in an area of steep switchbacks. While no damage was reported, these roads did become impassable and had to be cleared in the hours after the water receded. No injuries or fatalities were reported.

Wider weather episode

Unusually rich monsoonal moisture was in place on the morning of August 26th, with precipitable water close to 1.00 inch across eastern Utah and western Colorado. A jet streak moving in aloft brought not only additional moisture, but some extra lift as well. In addition, daytime heating on the complex terrain in this region help to spur on afternoon convection. As a result, widespread shower and thunderstorm activity developed during the afternoon, producing localized very heavy rain and high rainfall rates.

View location on OpenStreetMap → (37.2604, -109.9499)

Source: NOAA Storm Events Database, event_id 1291259. Narrative written by the NWS forecast office that issued the report.