A powerful thunderstorm swept through the Treasure Valley Friday night, June 27, 2026, delivering damaging winds, heavy rain, hail, and hundreds of lightning strikes across Ada County and neighboring counties — prompting a countywide disaster emergency declaration in Canyon County and an overnight response from road crews across the region.
Storm Brings Record Lightning, Heavy Rain to Treasure Valley
The National Weather Service issued a severe thunderstorm warning for the Boise metro area as the storm moved through, with wind gusts topping 50 mph in multiple locations. The strongest gust recorded was 53 mph in Caldwell, while Boise Airport clocked winds at 51 mph. Many communities across the valley experienced sustained gusts between 40 and 45 mph throughout the evening.
Rainfall exceeded one inch in several Treasure Valley locations. Homedale led all reporting stations with 1.54 inches, followed by Garden City north at 1.20 inches, Greenleaf at 1.47 inches, Caldwell at 1.13 inches, and a location four miles northwest of Boise at 1.19 inches. The National Weather Service received confirmed reports of more than an inch of rain at multiple sites across the valley.
Ada County recorded 100 lightning strikes during the storm — the second-highest single-day total for June in Ada County since the year 2000. Canyon County logged 51 strikes, while Owyhee County saw the most dramatic lightning activity with 553 recorded strikes. Hail also accompanied the storm, and while the stones were relatively small in size, National Weather Service lead meteorologist Josh Smith noted that volume was the story: “It was small hail, but there was an awful lot of it.”
Road Closures, Mudslides, and Flooding Force Emergency Response
The storm triggered significant infrastructure problems across the area. Major flooding on Highway 95 forced multiple road closures between Payette and Fruitland, cutting off travel along a key corridor in the region. Mudslides were reported on Highway 52 between NE 10th Avenue and Memorial Park near New Plymouth, adding to hazardous driving conditions for motorists.
The Canyon County Board of Commissioners declared a countywide disaster emergency in response to the storm’s impact. A flood advisory remained in effect through 7:30 p.m. Mountain time covering Parma, Wilder, Greenleaf, and Adrian, Oregon.
In Ada County, Ada County Highway District crews worked through the night to address flooding and road hazards left by the storm. The overnight mobilization reflected the scale of damage the fast-moving system caused across local roadways and drainage infrastructure.
Impact on Ada County Residents and Surrounding Communities
For Ada County homeowners and drivers, Friday night’s storm served as a reminder of how quickly conditions in the Treasure Valley can deteriorate during late-spring and early-summer weather events. Garden City, located north of Boise, recorded some of the highest rainfall totals in the metro area, and the concentration of lightning strikes across Ada County was historically notable for June.
Communities to the west, particularly in Canyon County, bore much of the brunt of the storm’s most damaging rainfall and flooding. The emergency declaration there signals that local officials expect recovery and cleanup to extend well beyond the immediate aftermath of the event.
What Comes Next
Residents across Ada County and the broader Treasure Valley should prepare for continued unsettled weather through the weekend. The National Weather Service is forecasting rain Saturday morning followed by afternoon showers and additional thunderstorms. Sunday’s forecast calls for showers pushing in from the north, with mountain areas above 6,000 feet possibly seeing snow.
Drivers are urged to remain alert for standing water on roadways and to check road conditions before traveling on highways in Canyon County and western Ada County. With another round of storms possible Saturday afternoon, additional flooding cannot be ruled out in low-lying and already-saturated areas.
Ada County residents can monitor updates from Idaho’s expanding statewide weather and wildfire monitoring network and should heed any flood advisories or warnings issued by the National Weather Service for the region through the weekend.