---
title: A Wildfire Can Flood a House Miles Away, Years After the Burn
description: In New Mexico, up to 60 percent of the year's rain falls July to September, and ground burned by wildfire sheds it like pavement for years.
author: Darie Nani (Editor-in-Chief)
updated: 2026-08-02T05:19:11.694Z
canonical: https://richdadmagazine.com/article/monsoon-burn-scar-flash-flooding-southwest
image: https://cdn.nanimediahouse.com/monsoon-burn-scar-debris-flow-78262.webp
categories: Real Estate
content_type: News
region: United States
publication: Rich Dad Magazine
schema_type: Article
---

A house in Arizona or New Mexico can flood in a storm that never rained on it. The water arrives from somewhere else, often off ground that burned in a wildfire years earlier and has not taken up rain properly since.

The North American monsoon runs from June 15 to September 30, and the National Weather Service office in Phoenix calls it the most dangerous time of year weather-wise in the Southwest. In New Mexico the season does most of the year's work. The southwestern corner of the state [receives about 50 to 60 percent](https://www.weather.gov/abq/northamericanmonsoon-intro) of its annual precipitation in July, August and September, and the central and northern parts receive 40 to 50 percent over the same three months.

How much actually falls swings hard from year to year. New Mexico averaged 4.82 inches of rain across July and August between 1950 and 2017. The state took nearly double that in 2006, and only 2.30 inches in 2003. Forecasters call the wet, active spells bursts, and the drier stretches between them breaks.

Some of that swing is set months earlier, in winter. A study published in 1998 documented an inverse relationship between the two seasons: wet winters are often followed by a drier than normal monsoon, and dry winters by a wetter one. Winters that leave snowpack below 50 percent are generally followed by summers with above average precipitation. The record wettest monsoon, in the summer of 2006, followed an exceptionally dry winter.

## Rain Lands in One Place and Floods Another

Summer thunderstorms here drop more water than the ground can absorb. On flat ground it ponds and stands; on a slope it runs off fast. The broken terrain of New Mexico then carries it, and the Weather Service is blunt about where it ends up: water is channeled to locations that have not even received recent rainfall. A property can take on water from a storm its owner never saw.

## Flash Floods Give Minutes, Not Hours

Flash floods usually arrive within six hours of the rain that caused them, and the Weather Service describes them as normally the most dangerous of floods, often leaving only minutes to react before impacts begin. Water levels can rise several feet in that time. The flow rolls rocks, tears out trees, sweeps away cars and trucks, and destroys buildings and bridges.

Where rain saturates soil until it turns into what the Weather Service calls very runny mud, that mud races downhill picking up fallen branches, tree trunks and rocks. A debris flow like that can bury a home.

## Burned Ground Sheds Rain Like Pavement

A fire changes what happens on that ground for years afterwards. When vegetation burns at high intensity it vaporizes water repellent compounds, which then condense on the ground and stop the soil absorbing water. A high intensity burn, the [Weather Service says](https://www.weather.gov/abq/northamericanmonsoon-flashfloods), can leave ground as water repellent as pavement, which means much less rainfall is needed to cause a flash flood.

Water running through a burned area erodes it quickly and picks up ash, soil, trees and boulders. The force of that flow can damage or destroy bridges, roads and buildings even miles away from the burn. Flooding off the Hermit's Peak and Calf Canyon burn scar sent tons of rock and mud into Gallinas Creek, near New Mexico State Route 65.

Most burn areas stay prone to debris flows for at least two years, and sometimes as many as four or five. Each one carries a risk of its own, which the Weather Service says depends on how close the population centers are, how severely and how widely the area burned, how steep the terrain is, and more.

## A Watch Means Get Ready, a Warning Means Go

The Weather Service issues a Flash Flood Watch when the ingredients are starting to align for flooding. During a watch it advises exercising caution, listening for bulletins, watching for signs of rising water, and being ready to move to higher ground at a moment's notice. Between watch and warning sits a third alert, an Urban and Small Stream Flood Advisory, for minor flooding in low lying and flood prone areas.

A Flash Flood Warning means a flash flood is happening or is imminent. Your margin of safety, in the Weather Service's own words, may be counted in seconds. Get out of the danger zone and to higher ground immediately. If you cannot leave and have to shelter in place, the instruction is to get to the highest point inside the home. Go up, not out.

Most flooding deaths happen in vehicles, usually when a driver crosses a flooded road or goes around a barricade. Twelve inches of swift water will sweep a small car away, and 18 to 24 inches can carry off a large SUV, truck or van. There are thousands of low water crossings and dips across the Southwest that flood every summer.

Before the season starts, the Phoenix office suggests securing loose outdoor furniture and garbage cans or moving them indoors. Thunderstorm gusts in the Southwest almost always exceed 40 miles an hour, and the strongest exceed 100.

## FAQ

**Q: When does the North American monsoon season start and end?**
The season runs from June 15 to September 30. Onset comes later than the start date in places: in the central Rio Grande valley, including Albuquerque, active monsoon rain usually begins around July 9.

**Q: What is burn scar flash flooding?**
When vegetation burns at high intensity, it vaporizes water repellent compounds that condense on the ground and stop the soil absorbing water, leaving it as water repellent as pavement. Much less rainfall is then needed to cause a flash flood. Water running through the burned area picks up ash, soil, trees and boulders, and the flow can damage or destroy bridges, roads and buildings even miles from the burn. Most burn areas stay prone to flash floods and debris flows for at least two years, and sometimes as many as four or five.

**Q: What is the difference between a flash flood watch and a flash flood warning?**
A watch means flooding is possible and the weather ingredients are starting to align. The Weather Service advises caution, listening for bulletins, watching for rising water, and being ready to move to higher ground at a moment's notice. A warning means a flash flood is occurring or is imminent, your margin of safety may be counted in seconds, and you should get to higher ground immediately.