Why is Extreme Flooding Happening More Often?

Over the past two decades, I’ve covered so many different weather events as a meteorologist. Throughout my career, I’ve been reporting more extreme flooding. Flooding is the second lead cause of weather related fatalities in the United States. The recent devastating flooding in Texas and the most recent flash flooding at the Grand Canyon are reminders that flooding can happen quickly, unexpectedly and with deadly consequences.

The July 2025 flooding across the Texas Hill Country included widespread 1-in-1000-year precipitation event that led to extreme flooding, according to NOAA.

Different Types of Extreme Flooding 

What Is a “100-Year Flood”?

Contrary to what one might think, these so-called “100 year floods” does not mean a flood that happens once every 100 years. It’s a flood event that has a 1% chance of occurring in any given year at a particular location. So, if your area experienced a 100-year flood last year, that does not mean you are safe for the next 99 years.

What About a 500 and 1000 Year Flood?

A 500-year-flood has a similar concept. Instead of a 1% probability, it has a 0.2% chance of occurring in any given year. In the case of a 1000 year flood, the event can happen every 0.1% in a year. Again, it doesn't mean the flood can only happen once every 500 or 1000 years.

Although the odds of these types of events appear low, it’s happening at a more rapid rate which leads to the question, “Does climate change have anything to do with it?” 

These probabilities are based largely on historical observations and statistical modeling. As our climate changes, the conditions used to calculate those probabilities can also change.

As a meteorologist, I think it’s important to understand what these terms actually mean.

Why Does Extreme Flooding Happen More Often?

Water vapor and rising temperatures have become two of the biggest factors. A warmer atmosphere can hold more moisture. Generally, for every 1°C (1.8°F) of warming, the atmosphere can hold roughly 7% more water vapor. This DOESN’T mean every storm will produce 7% more rain.

However, if the right ingredients come together which includes loads of moisture, instability, and lift, then there is an increased risk for more rain to fall in a short period of time resulting in flash flooding.

But let’s be clear; climate change doesn't mean that every flood is caused by climate change. Weather is complicated and happens day to day. Flooding depends on many factors—including rainfall rates, soil conditions, terrain, drainage, development and the location of rivers and streams. As the climate becomes warmer, the odds of more intense rainfall events will likely increase.

Texas: A Catastrophic Example that Proves the Increase Frequency of Major Flooding

A major flash-flood event struck the Texas Hill Country on July 16,2026, including the Guadalupe River in Kerr County. The river at Hunt rose dramatically—from about 9 feet to 19 feet in roughly an hour, and later reached around 37 feet. The nearby Pedernales River also experienced a major flood wave. This flooding along the Guadalupe River was an extreme flood event, with the river reaching levels near the 1-in-100-year flood level at some locations, according to NOAA.

Now as for the devastating flooding that struck parts of Texas in July 2025, NOAA classified the Texas Hill Country disaster as a 1-in-100- to 1-in-1,000-year flood event. In other words, this wasn't simply another heavy rain event—it was an extraordinarily rare flooding event.

The agency also recorded rainfall rates of 2-3 inches per hour with up to 11 inches around the river's headwaters and at least 135 people died as a result.

According to climate scientists, it's difficult to say that climate change “caused” any individual flood.

But there is strong scientific reasoning behind why a warmer climate can make extreme rainfall more likely.

Warmer air can hold more moisture, while warmer Gulf waters can provide additional moisture to the atmosphere.

When a weather disturbance comes along and allows that moisture-rich air to rise, the result can be incredibly heavy rainfall in a short amount of time.

And that is when the situation can quickly go from “it's raining” to “we have a life-threatening flood.”

Rainfall isn’t the Only Factor in Extreme Flooding 

The Grand Canyon’s most recent flooding is a reminder that you don't need a hurricane or tropical storm to produce a catastrophic flood.

On August 29, intense thunderstorms produced significant flash flooding in Bright Angel Canyon and around Phantom Ranch.

The flooding destroyed numerous footbridges, damaged infrastructure and led to evacuations. Tragically, people lost their lives, and search-and-rescue operations followed.

The National Park Service said the flooding caused significant damage throughout the canyon. Additionally, the Grand Canyon was impacted by the 2025 Dragon Bravo wildfire.

The wildfire destroyed vegetation making the landscape more vulnerable to flooding. Vegetation can absorb water mitigating runoff, burnt soils repel water allowing rainwater to rapidly run downhill.

When steep canyon terrain is added to the equation, intense thunderstorms and a moisture-rich atmosphere becomes the perfect recipe for dangerous flash flooding.

Recent analysis of the Grand Canyon event points to this combination of factors, including the burn scar, drought, unusually high atmospheric moisture and a warming climate.

In other words, the rain was only part of the story.

Is Climate Change Making Flooding Worse?

This is where we need to be careful.

As a meteorologist, I don't want to tell you that climate change caused a particular flood unless scientists have specifically conducted an attribution study showing that connection.

Weather events are influenced by many factors.

But we do know something important: a warmer atmosphere can hold more moisture, and that can increase the potential for heavier precipitation.

Research and climate assessments show that extreme precipitation has increased in many parts of the United States, although the trends vary by region.

In Texas, for example, climate scientists have documented increases in extreme rainstorms and expect the frequency of these events to continue increasing as the climate warms.

And that's why we sometimes hear the phrase “100-year flood.” If the underlying climate is changing, then the historical data used to determine flood probabilities may not perfectly represent the conditions we are experiencing today—or the conditions we may experience decades from now.

Flooding Is More Than Just Rain

It’s important to note that flood risk isn't only determined by rainfall totals. For example, two inches of rain falling over 24 hours is less of a risk than two inches falling in an hour. 

Also, flooding is less likely when two inches of rain falls on dry, absorbent soil than two inches falling on already saturated ground.

When it comes to terrain, a steep canyon can funnel water rapidly whereas a burned landscape may not absorb water the way it once did.

A highly developed area like New York City has more concrete and pavement, which can prevent water from soaking into the ground.

And a swollen river may already be running high before the next storm arrives.

All of these factors matter.

Flood Safety Tips

The flooding we've seen in Texas and now at the Grand Canyon is a reminder that extreme weather doesn't always look the way we expect it to.

It doesn't have to be a Category 5 hurricane.

It doesn't have to be a massive tornado.

Sometimes it's a thunderstorm that produces a significant amount of rain over a small area in a very short period of time.

And that can be enough to turn a normally peaceful creek, river or canyon into a life-threatening torrent.

Climate change is not the only reason we're seeing devastating floods. But a warmer atmosphere can provide one of the ingredients that makes extreme rainfall possible.

That's why understanding science matters.

The goal isn't to scare people.

The goal is to prepare.

Know your flood risk in your area.

Pay attention to watches and warnings. Always make sure your notifications are in the event of a flood emergency.

Have a weather radio in hand in case  you’re in an area where there’s more service.

Remember the mantra: “Turn around, don’t drown.” Never drive through flooded roadways.

And if you're hiking, camping or traveling in an area prone to flash flooding, remember that blue skies where you are don't necessarily mean you're safe. Rain falling miles upstream can send a wall of water downstream with little warning.

As we've seen far too many times, water always wins.

And when extreme rainfall meets vulnerable terrain, the difference between an ordinary storm and a disaster can come down to just a few inches of rain—and a very short amount of time.