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.
**NATIONAL** - The nation currently faces no active flooding threats, with river monitoring systems reporting normal conditions across all major watersheds. However, this calm period comes at a critical time as communities nationwide ramp up preparations ahead of hurricane season, with experts warning that the next era of Atlantic hurricanes could prove far more destructive than previous years. The temporary reprieve offers residents in flood-prone areas a crucial window to implement protective measures before severe weather arrives.
While no immediate flooding dangers exist, recent weather patterns across the country underscore the unpredictable nature of severe storms. Texas faces particular concern with forecasts warning that two months' worth of rain could fall within days, prompting authorities to issue flood risk warnings for Houston and surrounding communities through Memorial Day weekend. Meanwhile, severe thunderstorms have already caused widespread power outages and downed trees across Central Texas, with approximately 60,000 Boston residents currently without power following severe weather that swept through New England. The National Hurricane Center is actively monitoring tropical conditions as the 2026 season approaches, with new forecasts warning of a potentially powerful "super El Niño" that could dramatically impact weather patterns.
Coastal communities are taking proactive steps despite current calm conditions. St. Petersburg residents continue rebuilding efforts from previous storms as the city launches new resilience planning discussions, while Hillsborough County has updated hurricane evacuation zones. In North Carolina, Swannanoa and Rosman have received $1.2 million for flood resilience projects following previous flooding events. Texas communities are installing AI-powered flood sensors in Friendswood and League City to improve early warning capabilities. Experts emphasize that Hurricane Preparedness Week promotes the critical importance of pre-season preparation, as studies show growing hurricane and flood exposure across major U.S. housing markets. With insurance companies increasingly abandoning high-risk areas, homeowners must act now to protect their properties and families. The UN Weather Agency has warned of escalating climate extremes, making this preparation window essential for communities nationwide before the next major weather event strikes.
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.