Flash Flooding

Climate change is linked to flash flooding in Texas through several key mechanisms:

• Increased Atmospheric Moisture: Warmer global temperatures cause more water to evaporate from oceans and land surfaces, including the Gulf of Mexico. This increased moisture in the atmosphere means that when weather systems develop, they have more water vapor to draw upon, leading to heavier rainfall.
• Intensified Rainfall: The warmer atmosphere's capacity to hold more water vapor contributes to more intense rainfall events. Scientists indicate that the amount of rain expected on the wettest days of the century has increased by nearly 20% in some areas from 1980 to 2020, suggesting that storms that once occurred once a century may now happen more than twice as often.
• Increased Frequency of Extreme Precipitation: Climate change is expected to lead to a growing trend of both frequency and intensity of heavy precipitation events in Texas.
• Stark Divide in Weather Extremes: Climate change contributes to a growing gap between wet and dry areas within Texas. While some areas may experience more intense rainfall and flooding, others are likely to face increased drought severity due to higher temperatures and altered precipitation patterns.
• Exacerbation of Existing Flood Risks: While climate change may not be the sole cause of any specific flood event, it exacerbates many factors that increase flood risk, such as influencing the frequency and intensity of extreme precipitation. For example, studies following Hurricane Harvey in 2017 suggested that climate change may have made the rainfall 15% more intense and three times more likely to occur. 

In essence, a warming climate creates conditions more favorable for severe rainstorms and increases the potential for significant flash flooding in Texas by increasing the amount of moisture in the atmosphere and intensifying rainfall events.  

Climate change contributes to flash flooding in Texas through several interconnected factors: 

• Increased Atmospheric Moisture: A warmer atmosphere can hold more water vapor. As global temperatures rise due to climate change, the air becomes more capable of holding and subsequently releasing large amounts of moisture, leading to intense rainfall events.
• More Intense Rainfall: This increased atmospheric moisture capacity contributes to heavier and more intense rainfall events. Studies suggest that storms that once occurred once in a century are now likely to happen more than twice as often due to climate change, according to Texas A&M research. This translates into more frequent instances of extreme precipitation in Texas.
• Amplified Effects: Climate change exacerbates factors that increase flood risk. For example, rising temperatures can increase evaporation rates, leading to drought conditions in some areas. Paradoxically, these dry soils can then quickly become overwhelmed and contribute to rapid runoff and flash flooding when heavy rain does occur.
• Changes in Storm Patterns: Climate change can alter weather patterns and the frequency of storms. Scientists are seeing a trend of stronger and wetter storms increasing in frequency. 

In summary, climate change creates a situation where the atmosphere can hold more water, leading to heavier rainfall and more intense storms. This increased rainfall, combined with existing vulnerabilities like dry soils from increased evaporation, makes Texas more susceptible to flash flooding. 

5 sites

• Texas Suffers Deadly Flash Floods on July 4 | TIMEJul 4, 2025 — The National Weather Service in San Angelo also urged residents to stay off the roads. “More than an entire summer's worth of rain fell in some spots in just a ...Time Magazine
• Texas 2036. 2024 Climate ReportApr 22, 2024 — EXTREME RAINFALL. ... xxiv Much of the pattern is governed by the fact that Hurricane Harvey and Tropical Storm Imelda hit southeast Texas rather than South Tex...Texas 2036
• Texas A&M Study Reveals Climate Change's Impact On ...Oct 2, 2024 — * The heavy rain that hit much of the southeastern U.S. during Hurricane Helene is part of a bigger, long-term trend, according to recent research led by Texas ...Texas A&M College of Arts and Sciences

Texas Suffers Deadly Flash Floods on July  4.

Water rises from severe flooding along the Guadalupe River.in Kerr County, Texas on Friday, July 4, 2025. Parts of central Texas are in a state of emergency after an estimated 5-11 inches of rain prompted flash floods, forcing residents to evacuate on July 4.

Authorities in the city of Kerrville, about an hour northwest of San Antonio, confirmed at least six fatalities, according to the Kerr County Lead, and urged displaced people to gather at a local Walmart that’s being used as a reunification center. Police ordered people who live close to the Guadalupe River to evacuate to higher ground as the river swelled to its second-highest height on record.

Roads and streets are flooded, and “residents are encouraged to shelter in place and not attempt travel,” according to a statement from the Kerr County Sheriff’s Office. The National Weather Service in San Angelo also urged residents to stay off the roads. 

“More than an entire summer’s worth of rain fell in some spots in just a few hours, quickly overwhelmed dry soils and created significant flash flooding,” CNN reported. “Central Texas is currently home to some of the worst drought in the United States and bone-dry soils flood very quickly.”

Flash floods are the most severe flood warning. In 2024, the National Weather Service recorded 91 flash flood emergencies, more than any other year since it started using that terminology in 2003.

The July 4th flooding in Texas is just the latest example of storms becoming more severe in the era of climate change. Strong and wetter storms are increasing in frequency. The warmer the atmosphere gets, the more water it’s able to hold, and subsequently dump over land, according to the National Resources Defense Council (NRDC). As ocean temperatures rise, glaciers melt, and sea levels rise, increasing the risk of coastal flooding. As the NRDC puts it, “While our warming world may not be the only or most direct cause of any given flood, it exacerbates many of the factors that increase flood risk.”

How global warming intensifies flash flooding

Global warming intensifies rainfall, leading to more frequent and severe flash flooding in rivers. This occurs because warmer temperatures increase the atmosphere's capacity to hold moisture, resulting in heavier downpours and increased runoff, overwhelming river systems. Additionally, rising temperatures can cause snow to melt earlier in the season, contributing to higher river flows and flooding. 

Here's a more detailed explanation:

• Increased Evaporation and Moisture Retention:As the planet warms, more water evaporates from oceans, lakes, and land surfaces. This moisture-laden air can then hold significantly more water vapor than cooler air. 
• Intensified Rainfall:The increased atmospheric moisture leads to more intense rainfall during storms, including atmospheric rivers, which are known for carrying vast amounts of water. 
• Reduced Snowpack:Warmer temperatures cause snow to melt earlier in the year, reducing the natural reservoir of water that historically helped sustain river flows throughout the dry season. This can lead to a greater volume of water entering rivers at once, increasing the risk of flooding. 
• Drier Soils:While increased rainfall can lead to saturation, heatwaves can also dry out soils, making them less able to absorb rainfall when it does come. This can exacerbate surface runoff and contribute to flash flooding. 
• Changes in River Flow:The combined effects of increased rainfall, snowmelt, and soil moisture can lead to significant changes in river flow, with higher flows and more frequent flooding events. 
• Impact on River Capacity:Heavy rainfall can cause soil erosion, depositing sediment into river channels. This sediment buildup reduces the river's capacity to carry water, making it more susceptible to flooding.