Flash Flood Warning Active in Southern Fremont County, Wyoming Until 9:30 PM MDT
The National Weather Service in Riverton, Wyoming has issued a Flash Flood Warning for southern Fremont County in central Wyoming, in effect until 9:30 PM MDT tonight (Saturday, September 19). The warning was issued at 6:25 PM MDT after Doppler radar indicated thunderstorms producing heavy rain, with between 2 and 3 inches already fallen. This is exactly the profile that turns into the interior flooding jobs restoration teams see most — rural flash flooding of streams, drainages, and low-lying areas. This is a live snapshot as of 5:30 PM PDT. Conditions change fast — always verify with the National Weather Service for your specific county or ZIP code.
Southern Fremont County — Flash Flood Warning
The warning comes from NWS Riverton (Wyoming), issued at 6:25 PM MDT on September 19, 2026, and runs until 9:30 PM MDT. Certainty is Likely, urgency Immediate, severity Severe.
Hazard: Flash flooding caused by thunderstorms. Source: Radar indicated. At 6:25 PM MDT, Doppler radar indicated thunderstorms producing heavy rain across the warned area. Between 2 and 3 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly, per the NWS alert verbatim.
Expected impacts: Flash flooding of small creeks and streams, as well as other poor drainage and low-lying areas.
Locations that will experience flash flooding: Mainly rural areas of southern Fremont County. The alert specifically names the following streams and drainages: Little Popo Agie River, Grant Young Ditch, Monument Draw, North Fork Ballenger Draw, Popo Agie River, and Government Draw.
The issuing office is NWS Riverton: weather.gov/riw.
Stay safe tonight
Turn around, don’t drown when encountering flooded roads — most flood deaths occur in vehicles. Be aware of your surroundings and do not drive on flooded roads. In rural areas, creeks and washes can rise in minutes, especially after dark. Please report observed flooding to local emergency services or law enforcement when you can do so safely.
If water gets into your home: stay out of standing water where electricity may be present, avoid the basement until the water recedes and power is confirmed off, photograph everything before cleanup (documentation matters for insurance), and then call a local restoration contractor — water left sitting starts a second wave of damage within a day.
What this means for restoration teams
This warning is a classic rural Wyoming flash flood: named drainages — the Popo Agie River and its tributaries — with 2 to 3 inches already down and radar-indicated storms still overhead. Restoration contractors in the Riverton and Lander corridor should read this as likely creek and stream overflow reaching outbuildings, basements, and crawlspaces in low-lying rural properties, plus washed-out rural driveways and access roads that delay response.
The damage categories to expect: interior water intrusion from rising creeks and saturated ground, soaked drywall and insulation in below-grade living space, mold risk within 24 to 48 hours in any structure that took standing water, and potential contamination from agricultural or septic-area runoff in rural drainages. Note the 2 to 3 inches already fallen — that is enough to push small streams like Government Draw and Monument Draw over their banks.
The play: stage equipment now, keep an on-call rotation through the evening (the warning runs to 9:30 PM MDT, and streams crest after the rain stops), and capture address, water source, and affected areas on the first call. Field discipline matters more at night: photo-document before mitigation, moisture-map every affected room, and keep the homeowner’s payment responsibility clear in writing before work starts.
FEMA & federal assistance
FEMA Helpline: 1-800-621-3362 (7 a.m.–10 p.m. local, 7 days a week). Apply at DisasterAssistance.gov, through the FEMA app, or find a recovery center at fema.gov/drc. Basic eligibility requires U.S. citizenship or qualified status, identity verification, proof of occupancy or ownership, and unmet needs not covered by insurance. Apply as soon as it’s safe to do so.
Looking ahead
The warning expires at 9:30 PM MDT. Watch for additional rounds of thunderstorms through the evening — the radar-indicated source means new cells can re-form over the same drainages. Creeks and streams in this area can crest hours after the rain stops, so the danger window extends past the official expiry. Water-intrusion calls typically start within hours of water receding and keep coming for days as people discover damage, so contractors should plan for a busy Sunday.
Sources & how to verify
- National Weather Service Riverton: weather.gov/riw
- Check active alerts for your county at weather.gov or your local NWS office page.
Verify conditions for your specific county or ZIP code at weather.gov before traveling or working in the warned area.
This post is for informational purposes and is not an official weather warning. Always follow instructions from local authorities and the National Weather Service.
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