Could It Happen Here?

After a devastating and deadly July of extreme flooding and rainfall across the country, what does the future hold for the Chesapeake region?

Water is a source of life, recreation, and connection but its power and force are often underestimated. Heavy rainfall can reduce visibility, leading to major car accidents; strong winds split trees and rip apart roofs; and excessive rain in a short amount of time yields another deadly natural disaster: flash flooding. 

Devastating flash flooding from heavy rains in Texas killed 134 people, many of them young summer campers, during the 2025 4th of July weekend. Roughly a week later on July 13, heavy rainfall flooded residents in Colonial Heights, Virginia. The next day on July 14, flash flooding closed subway lines in New York, killed two people in New Jersey, and flooded streets and basements in Pennsylvania. Then on July 19, sudden heavy rain and flooding left several people stranded in their cars throughout Montgomery County, Maryland. All these events beg the question, “Is this a sign of more to come?”

How does extreme rainfall affect our region?

Extreme rainfall results in increased polluted runoff into local creeks, streams, and rivers that eventually reach the Chesapeake Bay. For residents, heavy rainfall can result in damage and loss of property, time, money, and even life. For the Bay and its tributaries, it increases streamflow that uproots submerged aquatic vegetation, it changes salinity levels necessary for fish survival, and it limits the ability of the sun to reach life living in lower layers of the water.

Have extreme rainfall events gotten worse?

Extreme storm events have increased over the 20th and early 21st centuries. The Chesapeake Bay region has experienced similar trends to the rest of the northeast and mid-Atlantic U.S., including more annual rainfall and more frequent and intense extreme storms. In 2022, scientists at the National Oceanic and Atmospheric Administration created climate summary reports for each state in the country that include the following trends:

• Maryland: From 1995 to 2020, total annual rainfall was higher than the 1895–2020 long-term average. Extreme rainfall events of 2 inches or more occurred 2.5 days per year from 2005 to 2020 compared to the 1950–2004 average of 1.8 days per year.
• Pennsylvania: Days with rainfall of 2 inches or more have increased since 1900. The 2010s had years with multiple days of extreme rainfall, such as 2011 when the remnants of Hurricane Irene and Tropical Storm Lee drenched the state and caused massive flooding over a two-week period.
• Virginia: Total annual rainfall has increased since 1900 with many years exceeding the long-term average. The number of 2-inch extreme rainfall events has increased since 1990, with 2015–2020 having experienced the most days of extreme rainfall per year.

What does the future hold?

Rising air temperatures from climate change means the atmosphere can “hold” more moisture to fuel more rain and intensify storms. This relationship means that annual rainfall amounts and extreme rainfall events are more likely to increase in a warming climate. These events will worsen coastal flooding conditions in the Chesapeake Bay, where the sea level has risen twice as fast as the global sea level rise rate.

• Maryland: According to a June 2025 study from the University of Maryland, future climate projections indicate an increased probability of extreme rainfall events by the end of the 21st century. In the worst-case climate scenario, all Maryland counties could see at least a 30 percent increase in extreme event probability, with some counties experiencing a 60 percent increase.
• Pennsylvania: Heavy rainfall events will likely increase by an additional two days per year by 2050 and more than three days per year by 2100 according to the state’s 2024 Climate Impacts Assessment Report. Accounting for population growth, the total number of Pennsylvanians exposed to flooding will increase by 25–75 percent.
• Virginia: The Virginia Cooperative Extension projects that average annual rainfall will increase by 44–53 inches and extreme rainfall events will increase from 0.5–1.5 days per year during the late 20th century to 1–2.5 days per year during the mid 21st century.

Can we mitigate extreme rainfall events?

The first way to reduce the harm of extreme rainfall is to reduce stormwater runoff through better land management. Some solutions include:

• Improving soil health by increasing organic matter concentrations. This increases the capacity for the soil to retain water and reduce runoff.
• Reducing the amount of impervious surface areas (non-penetrable surfaces like asphalt and concrete) and increasing the amount of pervious surface areas (penetrable surfaces like soil and gravel). Water quickly runs off impervious surfaces, whereas pervious surfaces filter water through the ground, which is slowly released into nearby waterbodies.
• Planting riparian forest buffers to collect and absorb rainfall. Heavier rainfall increases surface water runoff, which carries with it more sediment, pollution, trash, and warmer water in urban areas. Riparian forest buffers filter and catch pollution before entering the waterbody, while shielding the waterbody itself from the rain. 
• Improving stormwater infrastructure to handle the expected increases in stormwater runoff. This will reduce road and residential backflow, keeping residents safe from flash floods and ensuring emergency services reach their destinations. Fortunately, many green solutions can help manage stormwater runoff while also cooling local areas.

The second, and perhaps the most important way to reduce the effects of extreme rainfall, is to slow down the rate and intensity of climate change through reducing our reliance on fossil fuels and increasing the adoption of renewable energy.