Real-time river flooding
across America.
Live USGS streamgauge readings, FEMA flood zones, NWS flood watches and warnings, and historical context — one map, refreshed throughout the day. Built for flood researchers, emergency managers, and outdoor recreationists.
What's happening right now
An AI-generated daily summary stitched from active streamgauge readings, NWS warnings, and watershed status.
A dangerous flooding crisis is unfolding across multiple states, with several watersheds experiencing streamflow levels exceeding 600% of normal while others face severe drought conditions that could exacerbate flash flooding risks. The most alarming situation is developing near Houston, Texas, where the Buffalo-San Jacinto watershed is recording a staggering 1,078% of normal flow—over ten times typical levels. This comes as forecasters warn of increasing rain chances in the Houston area with significant flooding potential, creating an immediate threat to millions of residents. Simultaneously, communities from Illinois to Nevada are grappling with extreme water level fluctuations that have overwhelmed drainage systems and threaten widespread property damage.
The St. Louis metropolitan area, including Cahokia and surrounding Illinois communities, faces a critical emergency with streamflow at 687% of normal in the Cahokia-Joachim watershed. Meanwhile, the Salt watershed near Phoenix, Arizona is experiencing flows at 670% of normal, threatening flash flooding in urban areas ill-equipped for such volumes. Las Vegas is similarly imperiled, with Las Vegas Wash recording 636% of normal flow. In Louisiana, communities along the Lower Sulphur watershed are seeing flows at 619% of normal. The Grand River region in Oklahoma is particularly vulnerable, with the Lower Grand watershed at 374% of normal despite the upper portions running critically low at just 15.8% of normal—a dangerous combination that can trigger sudden, catastrophic flooding downstream. The Vermilion River in Louisiana is flowing at 181% of normal, threatening Abbeville and surrounding Cajun communities.
In stark contrast, severe drought conditions in other regions are creating hardpan surfaces that cannot absorb rainfall, setting the stage for dangerous flash floods. The Wild Rice River in North Dakota is at a mere 20.3% of normal flow, while Little Cottonwood Creek near Salt Lake City runs at just 23.4% of normal. The Tombigbee River system in Alabama, serving Demopolis and surrounding areas, is critically low at 33% of normal, while the Des Plaines River near Chicago operates at just 30.5% of normal. Scientists confirm that climate change has made every studied hurricane wetter, with experts warning that "the worst inland floods are still to come." With hurricane season intensifying and 33 million coastal homes at risk, authorities urge immediate preparation and flood insurance verification.
Rivers currently flooding or rising
Live USGS streamgauge readings aggregated by river. Percent-of-normal compares current flow to the seasonal average.
| River | Observed (cfs) | Seasonal avg (cfs) | vs. Normal |
|---|---|---|---|
| Black Warrior River | 2,000 | 5,464 | 37% of normal |
| Green River | 1,100 | 1,796 | 61% of normal |
| Little Cottonwood Creek | 38 | 164 | 23% of normal |
| Wild Rice River | 134 | 660 | 20% of normal |
| Vermilion River | 2,740 | 1,516 | ↑ 181% of normal |
| Grand River | 1,028 | 6,522 | 16% of normal |
| Platte River | 407 | 1,490 | 27% of normal |
| Cedar River | 343 | 151 | ↑ 227% of normal |
| Samish River | 126 | 185 | 68% of normal |
| Tombigbee River | 14,780 | 44,660 | 33% of normal |
| Tolt River | 502 | 738 | 68% of normal |
Watersheds running elevated
Aggregated by HUC8 watershed code. Useful for catchment-level flood-risk assessment.
| HUC8 code | Watershed | Observed (cfs) | vs. Normal |
|---|---|---|---|
| h03160106 | Middle Tombigbee-Lubbub | 2,880 | 26% |
| h07140101 | Cahokia-Joachim | 4,340 | ↑ 687% |
| h10280103 | Lower Grand | 22,639 | ↑ 374% |
| h17110013 | Duwamish | 1,100 | 61% |
| h12040104 | Buffalo-San Jacinto | 1,090 | ↑ 1078% |
| h17110002 | Strait Of Georgia | 126 | 68% |
| h03160113 | Lower Black Warrior | 2,000 | 37% |
| h10200203 | Salt | 3,960 | ↑ 670% |
| h07120004 | Des Plaines | 288 | 31% |
| h10280101 | Upper Grand | 858 | 49% |
| h10240012 | Platte | 407 | 27% |
| h15010015 | Las Vegas Wash | 212 | ↑ 636% |
| h16020204 | Jordan | 38 | 23% |
| h03080103 | Lower St. Johns | 86,261 | 80% |
| h11140302 | Lower Sulphur | 398 | ↑ 619% |
| h17110012 | Lake Washington | 59 | 49% |
| h08080103 | Vermilion | 2,740 | ↑ 181% |
| h03160201 | Middle Tombigbee-Chickasaw | 11,900 | 36% |
| h09020105 | Western Wild Rice | 134 | 20% |
| h17110010 | Snoqualmie | 502 | 68% |
What causes river flooding
Flooding is rarely a single-cause event — multiple factors usually compound. The most common drivers across the U.S.
Heavy rainfall
Persistent rain saturates soils and overwhelms drainage networks. Tropical systems and atmospheric rivers are the worst culprits.
Rapid snowmelt
Spring melt pulses can deliver months of accumulated water in days — especially when warm rain falls on existing snowpack.
Ice jams
Breakup ice can block channels, forcing water to back up and inundate upstream banks. Common on northern rivers in early spring.
Storm surge
Coastal hurricanes push seawater inland. Surge combined with rainfall is the deadliest flood scenario in U.S. history.
Reservoir releases
Controlled dam releases can dramatically increase downstream flow. USACE and USBR publish release schedules, but conditions change fast.
Burn scars
Wildfire-stripped slopes can't absorb rainfall — even modest storms produce dangerous flash floods on burned watersheds for years afterward.
Flood preparedness checklist
Floodwaters rise faster than most people expect. The basics that save lives.
Flood map & river monitoring FAQ
What does "percent of normal" mean?
The current flow at a gauge compared to its seasonal average for this date. 100% means flow is right at the historical norm. 200%+ means twice the typical flow — a strong indicator of flood conditions on small-to-medium rivers.
What's the difference between a flood watch and a flood warning?
Watch: conditions are favorable for flooding within the next 12–48 hours. Warning: flooding is happening or imminent. Both come from the National Weather Service. Snoflo overlays both as toggleable layers on the map above.
How often does Snoflo's data refresh?
USGS streamgauge readings update every 15 minutes; we re-pull every hour. NWS warning polygons update as the NWS issues them — usually within 5 minutes. FEMA flood zones are static (the National Flood Hazard Layer is updated quarterly).
What is the FEMA flood zone layer?
FEMA's National Flood Hazard Layer (NFHL) shows the 1%-annual-chance ("100-year") and 0.2%-annual-chance ("500-year") floodplains. These are based on long-term hydrologic modeling, not current conditions. Useful for property risk; not a real-time signal.
Can I get an alert when my local river floods?
Yes. Save any USGS gauge as a favorite in the Snoflo iOS app, set a threshold (e.g. "alert me at 20 ft stage"), and you'll get a push the moment it crosses. Free with a Snoflo account.
Is Snoflo a substitute for official warnings?
No. Snoflo is informational. For life-safety decisions always follow guidance from local emergency management, the NWS, and law enforcement.