Flash Flood in Oglala Lakota County, South Dakota

Runoff from heavy rainfall caused flooding of farmland along the Cheyenne River. Standing water was reported in fields of over a foot deep. In-bank rises of over 9 feet occurred along the Cheyenne River causing flooding of the lower banks.

From June 2-4, 2026, a series of disturbances tracking across the region within broad zonal flow set off several rounds of thunderstorms to the region. A slow-moving front on June 2 set off the first round of thunderstorms, producing widespread heavy rain and localized flash flooding. The most significant impacts occurred in Oglala and surrounding communities, where 6 to 7 inches of rain fell in a short period, causing streets and ditches to fill extremely quickly. Some storms also produced large hail and strong winds. Some storms also produced large hail and strong winds.

June 3 brought another round of storms as a disturbance moved across the Northern Plains. Clearing over Wyoming and the Black Hills allowed storms to redevelop along a boundary across southern South Dakota. Several became supercells, including the storm that produced the rain-wrapped Ideal tornado in Tripp County. The tornado mainly affected agricultural land but damaged multiple outbuildings and caused additional RFD'related damage to a nearby modular home.

On June 4, the severe threat was more limited. Lower dewpoints over Wyoming and a strong cap over the Black Hills and western South Dakota kept storm coverage down, though a few storms still became severe with larger hail and strong wind gusts. A landspout also occurred in northeast Wyoming with one of the isolated storms.