The article reviews a long-running record of the United States’ most damaging high-volume precipitation events. It highlights how rainfall extremes have grown in frequency and impact over the past seven decades, and what attribution science says about the role of human-caused climate change.
Decades of extreme rainfall: what the record shows
Across 77 years of data from long-running weather stations, the contiguous U.S. has seen multibillion-dollar losses from storms that deliver vast amounts of rain over wide areas. Six of the top 10 highest-volume precipitation events occurred between 2016 and 2020.
Hurricane Helene in 2024 is a recent addition, underscoring a trend toward more frequent extreme rainfall. Most of these events were slow-moving, which concentrates rainfall and drives catastrophic flooding.
The earliest entry on the list, the 1962 Columbus Day Storm, likely operated outside the influence of modern climate change. The dataset used to compile the top-11 list relies on four-day totals over areas larger than 50,000 km², drawn from a consistent network of stations.
It includes both hurricanes and non-hurricane systems.
Patterns in rainfall totals and storm behavior
Several notable patterns emerge from the record. Many of the largest rainfall totals come from storms that stall or creep slowly, dumping rain over the same places for extended periods.
Attribution studies consistently find that human-caused climate change has increased the likelihood or intensity of several recent events, notably Hurricane Harvey and a major 2016 Gulf Coast rainfall event. Forward speeds of tropical cyclones appear to have slowed in some U.S. regions over the past century, amplifying totals when storms linger.
The top-11 list demonstrates that not all extreme precipitation requires hurricane-force winds. Non-hurricane systems feature prominently as contributing events as well.
- Hurricane Harvey (2017) — recorded unprecedented localized totals, with more than 60 inches of rain at two separate sites, contributing to estimated losses of about $165 billion (2026 USD).
- Tropical Storm Imelda (2019) — produced a 44-inch, three-day rainfall total near Fannett, Texas, illustrating how tropical storms can rival hurricanes for rainfall impact even without hurricane-wind strength.
- The 2016 Gulf Coast “no-name” storm — a non-hurricane system that inundated southern Louisiana and forced more than 30,000 rescues, highlighting the flood risk from high rainfall independent of tropical cyclone category.
- Hurricane Florence (2018) — stalled over the Carolinas, driving record river flooding and widespread damage inland from the coast.
- Hurricane Sally (2020) — slowed to speeds of about 2–3 mph, dumping 20–30 inches of rain along the Gulf Coast and sustaining flood risk well inland.
- 1962 Columbus Day Storm — the oldest entry on the list and, unlike many later events, is not considered to be driven by modern climate change.
- Hurricane Helene (2024) — added to the top-11, with attribution studies indicating a roughly 10% increase in rainfall and substantially higher odds for two- and three-day extreme totals, signaling an ongoing shift in rainfall patterns with climate change.
Attribution and future risk under climate change
Attribution studies—an evolving field that links observed events to underlying climate drivers—consistently point to human contributions increasing the risk of heavy rainfall in several recent events. For the 2020 hurricane season, climate change intensified extreme rainfall rates.
For Helene, researchers estimate meaningful increases in multi-day totals and their likelihood. If greenhouse gas emissions continue and global temperatures rise about 2°C above preindustrial levels, experts warn that such devastating rainfall events could become 15–25% more likely in affected regions.
This would amplify flood exposure for communities, infrastructure, and ecosystems alike.
Implications for communities, infrastructure, and policy
The record emphasizes the need for proactive adaptation and resilient design in water-management systems, floodplain planning, and emergency response.
Key focus areas include improved forecasting of slow-moving storms and higher-resolution rainfall data to guide infrastructure investments.
Targeted mitigation strategies can reduce vulnerability in flood-prone regions.
As the climate continues to warm, planners and policymakers should prioritize:
- Investments in flood defenses and drainage systems that can handle multi-day, high-intensity rainfall events.
- Enhanced land-use planning to limit development in high-flood-risk zones and to preserve natural flood buffers.
- Strengthened building codes and retrofitting programs to reduce damage and expedite recovery after extreme rainfall events.
- Improved communication and evacuation planning tailored to slow-moving storms that deliver prolonged rainfall.
- Ongoing public education about rainfall risk, climate trends, and personal preparedness.
Here is the source article for this story: Dangerous heavy rains are getting more likely and widespread