Flood Warning Issued for Big River at Byrnesville in Jefferson County

Alert Details

The National Weather Service in St Louis MO has issued a Flood Warning for the Big River at Byrnesville. This alert was issued on March 5 at 9:41 AM CST and remains in effect until early Monday morning, March 9. The warning is classified as a severe event with likely certainty.

Affected Areas

The warning specifically impacts the Big River at Byrnesville, located within Jefferson County, Missouri (MOC099).

What You Should Do

Residents and motorists are advised to “Turn around, don’t drown” when encountering flooded roads. Most flood-related deaths occur in vehicles. The National Weather Service recommends avoiding flooded areas and monitoring local stream information via official channels.

Expected Conditions

Moderate flooding is currently forecast for the region. As of 8:45 AM CST on Thursday, the river stage was recorded at 8.1 feet. The river is expected to rise above the flood stage of 16.0 feet late this evening. It is projected to crest near 21.5 feet on Saturday morning. For context, at a level of 22.4 feet, Twin Rivers Bridge Road must be closed.

Timeline

The Flood Warning is effective starting late this evening, March 5, 2026. The river is expected to remain above flood stage until late Sunday night, with the warning officially set to expire at 1:00 AM CDT on Monday, March 9.