Live flood monitor

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.

Last updated May 18, 2026 · 29 sensors live
Rivers above flood
11
Watersheds elevated
20
Active flood sensors
29
USGS gauges tracked
10K+
Layers
Flow vs. normal
< 50%
~ 100%
200%
500%+
Tiles © Mapbox · Data USGS, NOAA NWS, FEMA, NRCS · Click any feature for details · Multiple layers under your click aggregate into one popup.
Today's flood briefing

What's happening right now

An AI-generated daily summary stitched from active streamgauge readings, NWS warnings, and watershed status.

May
18
2026
Flood report
# CRITICAL FLOODING EMERGENCY: Multiple U.S. Regions Face Extreme Water Levels as Hurricane Season Intensifies

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.
Right now

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
By basin

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%
Background

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.

Safety

Flood preparedness checklist

Floodwaters rise faster than most people expect. The basics that save lives.

1
Never drive through floodwaterSix inches can stall a car; two feet floats most vehicles. Turn around — don't drown.
2
Monitor levels near youTrack the gauges upstream of your location. Snoflo's push alerts can ping you the moment a threshold is crossed.
3
Have an evacuation planKnow two routes out and where higher ground sits. If officials issue an evacuation order, leave — don't wait.
4
Move valuables upDocuments, electronics, and sentimentals to upper floors. Disconnect electrical at the main breaker if water enters the structure.
5
Trust official sourcesNWS warnings and local emergency management are the authoritative source. Snoflo data is informational; always cross-check.
6
After the water recedesDon't return until officials clear the area. Floodwater carries sewage, fuel, and downed power. Document damage before cleanup.
Frequently asked

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.