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Extreme Precipitation and Climate Change

Extreme precipitation—rain or snow events that far exceed typical amounts—is becoming more frequent and intense as the climate warms. Warmer air holds more moisture, increasing the likelihood of heavy downpours and associated hazards such as flooding, water quality issues, and landslides. Communities across the United States are already experiencing these growing risks as extreme precipitation trends accelerate.

Historical Conditions and Future Projections for Extreme Precipitation

Extreme precipitation events have increased in frequency and intensity in the U.S. and across many regions of the world since the 1950s. These events are defined as instances in which the amount of rain or snow experienced in a location substantially exceeds what is normal. In the contiguous United States, annual precipitation has increased by 0.2 inches per decade since 1901, with extreme precipitation events outpacing this trend. The Midwest and Northeast have experienced the most substantial increases in heavy precipitation events.

Scientists expect these trends to continue as the planet warms. For each degree Celsius of warming, the air’s capacity to hold water vapor increases by approximately 7 percent. An atmosphere with more moisture can produce more intense precipitation events.

Increases in the frequency and severity of heavy precipitation may not always translate into higher total precipitation over a season or a year. Some climate models project a decrease in moderate rainfall and an increase in the length of dry periods, offsetting the effect of extreme precipitation events.

Projected Changes to Precipitation Extremes at 2°C of Global Warming

Notes

This map shows the observed (top) and projected (bottom) change in the amount of precipitation falling in the heaviest 1% of events (99th percentile of the distribution). The numbers in black circles for the observed show the percentage change and illustrate that most of the increase in heavy precipitation events since 1901 has occurred in the last ~60 years. The projected amounts show two climate change scenarios, called Representative Concentration Pathways (RCPs): the map on the left is based on a lower amount of greenhouse gas emissions while the map on the right shows a higher concentration emissions scenario.

Source

Fifth National Climate Assessment, Climate Trends

Impacts of Extreme Precipitation

Extreme precipitation drives a wide range of cascading impacts, from dangerous flooding and landslides to degraded water quality and public health risks. These events also strain infrastructure, disrupt essential services, and generate significant economic losses as communities face mounting damage and recovery costs.

Public Safety and Health Impacts

The most immediate public safety and health impact of heavy precipitation is flooding. Flood risk is common in both rural and urban areas across the U.S., posing a direct threat to human life. Extreme precipitation can lead to multiple different types of flooding, from riverine and flash flooding to coastal flooding and storm surge, the latter of which is exacerbated by rising sea levels.

Extreme precipitation is often a fast-moving public safety threat. For example, Central Texas experienced an extreme case of “weather whiplash” in early July 2025, shifting abruptly from a prolonged multi‑year drought to a rare 1‑in‑1000‑year rainfall event that caused catastrophic flooding. The region had endured exceptional drought conditions since 2021, worsening agricultural losses, water scarcity, and land vulnerability. The sudden torrential rainfall destroyed infrastructure, resulted in significant and devastating loss of life—over 100 people, including 27 children, were killed—and drastically altered the landscape.

Extreme precipitation can also have more delayed public health impacts, which may pose challenges in urban areas where non-permeable pavement forces water to run off into sewer systems quickly, or where overwhelmed drainage systems can lead to flooded streets, sometimes days after a rain event. When extreme precipitation causes flooding, it impacts the built environment, increasing the risk of mold growth in homes and other buildings and posing threats to human health.

Infrastructure Impacts

Heavy precipitation increases the risk of landslides. This occurs when above-normal precipitation raises the water table and saturates the ground, leading to slope instability. Washington state, which has a particularly high risk of landslides due to its terrain, anticipates these hazards will become more frequent as climate change-driven increases in heavy rainfall intensify.

Regions that experience substantial drought conditions are also at risk of landslides and debris flows when met with extreme precipitation. In December 2025, Southern California experienced several atmospheric rivers , extreme rainfall events during which water vapor from the tropics was transported in long bands along wind currents. The region reported its wettest Christmas Eve and Christmas Day on record with one region of the Ventura County mountains receiving more than 15 inches of rain. The deluge, following a prolonged drought in the region, triggered debris flows that damaged homes and property.

Extreme precipitation can also degrade water quality, harming human health, aquatic ecosystems, and fishery operations. Stormwater runoff, which often contains pollutants such as heavy metals, pesticides, nitrogen, and phosphorus, can end up in lakes, streams, and bays. This issue is especially prevalent in cities that use a combined sewer system, in which stormwater and wastewater are mixed, treated, and released in the same system. Heavy rainfall can overwhelm such systems, sending excess stormwater, wastewater, and untreated sewage directly into bodies of water. Extreme rainfall in the summer of 2022 led to flooding that overwhelmed water treatment plants in Jackson, Mississippi, killing three people and leaving more than 150,000 people without drinking water.

Economic Impacts

Extreme precipitation can produce economic impacts through several different channels. Flooding damages property and infrastructure, and shuts down regular business and commercial services. Precipitation can lead to power outages, disrupting regular business operations. When extreme precipitation is accompanied by other severe storm hazards—such as hail and damaging winds—the economic cost of damage and recovery is staggering; in 2025 alone, severe storms (including heavy rain, hail, winds, and tornadoes) in the U.S. are estimated to have cost $50.7 billion.

Flood recovery and rebuild costs are often a significant component of the total cost of extreme precipitation impacts. For example, in late July of 2022, extreme precipitation caused 8-12 inches of rainfall around St. Louis and 5-10 inches across eastern Kentucky, leading the North Fork of the Kentucky River to reach a new peak height. The cost to rebuild after the 2022 flooding in eastern Kentucky is estimated to be anywhere from $450 to $950 million.

How to Build Resilience to Extreme Precipitation

To reduce the likelihood of extreme precipitation events, it is critical to address the greenhouse gas emissions driving them by reducing fossil fuel use and taking other emissions-reduction actions. Simultaneously, communities can build resilience against the damaging effects of extreme precipitation by:

  • Updating zoning and building codes to place development in lower‑risk, higher‑elevation areas that can better withstand future flooding.
  • Investing in green flood‑control infrastructure—such as green roofs, trees, and wetlands—to improve stormwater management and provide added environmental benefits.
  • Limiting non‑permeable surfaces or replacing them with green infrastructure that absorbs floodwater and reduces runoff.
  • Incentivizing residents to adopt flood‑risk‑reduction measures like floodproofing and elevating homes.
  • Separating stormwater and wastewater systems and expanding holding ponds or treatment capacity to prevent sewage overflow.
  • Encouraging residents to purchase flood insurance, with communities earning reduced rates by implementing risk‑reduction strategies.
  • Creating strong flood‑warning systems to alert residents promptly.

Our publication “Resilience Strategies for Flash Flooding” provides further detail on many of the strategies above, along with co-benefits and implementation examples that can help state and local governments plan these strategies more concretely in their communities.

Other Tools and Resources:

The Climate Mapping for Resilience and Adaptation portal helps communities understand and plan for their climate risks today and in the future, including a real-time map of wildfire, drought, flooding, and extreme heat across the United States.

Learn more about resilience through our Climate Resilience Portal.

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