Wildfires from 2024 through this summer left scars above dozens of American towns. A very strong El Niño is now steering storms at some of them and away from others. This table sorts out which is which.
Compiled September 11, 2026. Fire and outlook data current as of that date.
This is journalism, not an engineering assessment. It is meant to tell you whether your watershed belongs in the conversation, and nothing more.
In an emergency, the National Weather Service warning on your phone outranks everything here. Act on it first and read later.
Two things decide whether a burn scar becomes a flood: how fresh and steep it is, and how much rain is headed for it. Right now those two factors point in opposite directions. The 2026 fire season was concentrated in the Pacific Northwest and Great Basin — exactly where a strong El Niño tends to suppress winter precipitation. The scars sitting under the wet side of the forecast are mostly in the Southwest, the southern Rockies, and California.
Every fire below burned at least 10,000 acres between January 2024 and September 2026 and left a scar with a community in its runoff path. Tap any row for the rainfall numbers and the reasoning behind the rating.
| Communities at risk | Outlook to mid-2027 |
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No scars match those filters. Try widening the search.
Post-fire flooding does not work like ordinary flooding. It is driven by short, violent bursts, not by storm totals, which is why the same three numbers appear in every row.
The USGS models post-fire debris flow against a design storm with a 15-minute peak intensity of 24 millimeters per hour — about a quarter inch of rain in fifteen minutes. That is roughly where burned ground starts sending material downhill, and it recurs every one to five years across most of the West.
Treat it as a benchmark rather than a number for your canyon. See the note below on why.
What a real storm has already dropped on that scar, where a gauge or a warning recorded it. Beulah, Colorado took one to three inches in an afternoon this July and got debris flows that destroyed homes and moved bridges. Where no event is on record, the row gives the design storm instead.
The regional ceiling: roughly what a very rare day of rain delivers in that part of the country. It tells you the upper bound a watershed has to handle. On an unburned slope it is a manageable number. On a fresh scar it is not.
A USGS paper published on September 1, 2026 is worth knowing about if you plan to lean on these thresholds. The model the agency has used for years, called M1, was calibrated on a debris-flow inventory from southern California and then applied across the western United States. Testing showed it overpredicts debris-flow likelihood and underpredicts the rainfall needed to trigger one in several places — Arizona, northern California, Colorado, and New Mexico among them. In other words, in exactly the states where this table finds the most exposure, the old thresholds were probably too low and the old likelihoods too high.
The replacement rebuilds the inventory to 3,788 observations from 67 burned areas and fits separate coefficients for three ecoregions: Mediterranean California, the Upper Gila Mountains, and the Western Cordillera. The updated models outperform M1 by roughly 15 to 60 percent and produce thresholds that track regional rainfall climatology more honestly. Each row in the table above notes which of those three regions it falls in — and, for the Great Basin, the Colorado Plateau, and Texas, that it falls in none of them and is covered only by the general model.
Fires of 10,000 acres or larger that burned between January 1, 2024 and September 11, 2026 and left a scar with an identifiable community in the runoff path. Two exceptions: the Salt Fire near Ruidoso is below the threshold but is folded in with the South Fork Fire, because the National Weather Service warns on the two scars as one system.
A large number of fires cleared 10,000 acres in this period without earning a place here. Grassland and rangeland fires on flat ground — most of the enormous Nebraska, Kansas, Oklahoma, and Texas Panhandle fires of 2026 — increase runoff but do not generate the confined, high-velocity debris flows this table is about. So do the Everglades and boreal Alaska fires. Scars with no community downstream are also left out, however large. The mechanism needs three things at once: burned ground, steep confined channels, and someone living below them.
A judgment, not a model output, combining four inputs: how recently the fire burned, the steepness and confinement of the drainages below it, how many people sit in the runoff path, and what the seasonal precipitation outlook says for that region through mid-2027. Scars that have already produced flash flood warnings, emergencies, or damaging debris flows are rated high regardless of the other factors — a watershed that has done it once will do it again. The USGS notes that post-fire debris flow hazard stays elevated for roughly two to five years, which is why 2024 scars carry lower ratings than 2026 scars of similar character.
The obvious upgrade to this table would be the basin-level numbers the USGS produces for individual fires: the likelihood that a given drainage produces a debris flow, and the volume it would carry. Those exist, and for many of these scars they have been published. They are not reproduced here, for two reasons.
The first is practical. The results live in an interactive dashboard and in versioned geospatial data releases, not in a table anyone can transcribe, and a percentage copied out of context loses the basin it belongs to. The second is that pointing you at the source is better than paraphrasing it. Every row links to the USGS dashboard, where you can search the fire by name and see the actual drainages, which is the resolution at which this hazard is real. Not every fire receives an assessment — the USGS conducts them for select fires, generally where an agency partner requests one and supplies the burn-severity data.
A low rating is not a guarantee and a high one is not a prediction. Post-fire flooding turns on where a single thunderstorm cell parks, and no seasonal outlook resolves that. The list is a way to know whether your watershed is in the conversation. Your county's floodplain office, your local National Weather Service forecast office, and the USGS post-fire debris flow assessment for your specific fire are where the conversation continues.