Climatology

Climatology of Weather and Climate Disasters

The charts above show the 46-year history of U.S. ‘compound extremes’ (e.g., billion dollar disaster events that occur at the same time or in sequence). The physical and socioeconomic impacts of compound extreme events (such as simultaneous heat and drought, wildfires associated with hot and dry conditions, or flooding associated with high precipitation on top of snow or waterlogged ground) can be greater than the sum of the parts (National Academies of Sciences, Engineering, and Medicine. Compounding Disasters in Gulf Coast Communities 2020-2021: Impacts, Findings, and Lessons (2024); Multi-Hazard Mitigation Council. Natural Hazard Mitigation Saves (2019); 4th and 5th U.S. National Climate Assessments (2017, 2023)).

Over the last five years (2020-2024), there were just 16 days on average between U.S. billion-dollar disaster events compared to 82 days in the 1980s. Shorter time intervals between disasters can mean less time and resources available to respond, recover and prepare for future events. This increased frequency of events produces cascading impacts that are particularly challenging to vulnerable populations.

The 46-year climatology of U.S. billion-dollar disasters offers a view of risk from extreme events, which are often seasonal in nature. For example, during the spring months (March-May) severe storms including tornadoes, hail and high winds often occur in many central and southeastern states. Severe convective storms (i.e., tornado, hail and high wind damage) have the highest count of billion-dollar disasters. Billion-dollar severe storm events have caused $37.9 billion in damage on average over the last five years (2020-2024). Below is a StoryMap describing the impacts of May 2024 severe storm events across the nation: We May Not Be in Kansas Anymore

During the spring months there is also potential for major river flooding (i.e., deep blue events in chart above). U.S. springtime flooding from snowmelt and/or heavy rainfall is a persistent hazard that affects many towns and agricultural regions within the Missouri and Mississippi River basins, among others. Of note, there were more billion-dollar flood events from 2010-2024 (26 events) than in the 1980s, 1990s and 2000s combined (19 events; all flood events CPI-adjusted to 2024 dollars).

During the fall season, Gulf and Atlantic Coast states experience their hurricane season peak during August and September (i.e., yellow events in chart above). Hurricanes are the most costly hazard type in our analysis since 1980, with an average cost of $23.0 billion per event. Understanding the multiple types of hazard risk associated with hurricanes is crucial given their impacts extend hundreds of miles inland. Below is a StoryMap describing the impacts of hurricanes and how to better understand their risk they present: How data from NOAA can help inform and prepare the public

For example, in 2016-2018, the U.S. was impacted by six separate billion-dollar hurricanes (Hurricanes Matthew, Harvey, Irma, Maria, Florence, and Michael) with an inflation-adjusted loss total of $423.2 billion and 3,318 fatalities. As a comparison, the U.S. also experienced a series of active hurricane seasons from 2003-2005 where nine separate billion-dollar hurricanes (Hurricanes Charley, Ivan, Katrina, Rita, Wilma, etc.) made landfall, with an inflation-adjusted loss total of $363.3 billion and 2,225 fatalities. As another concerning trend, the U.S. has been impacted by landfalling Category 4 or 5 hurricanes in six of the last eight years (Hurricanes Harvey, Irma, Maria, Michael, Laura, Ida, Ian, and Helene), which is the highest frequency on record (AOML,2025).

The peak of the western U.S. wildfire season occurs during the fall months of September, October and November (i.e., orange events in chart above). California, Oregon and Washington are states that often face wildfire risk and related poor air quality for weeks to months. Western wildfire damage during the 2017-2021 period was historic — exceeding $90 billion in 2024 dollars. The multi-year, historic western drought (2014-2016) and the continual growth of the built environment along the wildland-urban interface likely contributed to the catastrophic wildfires of 2017-2021. Seventeen of the 20 largest and most destructive wildfires in terms of the number of buildings destroyed have occurred since the year 2000 (CalFire, 2025). The Los Angeles wildfires in January 2025 were the costliest event so far this year as well as the costliest wildfire event on record — exceeding $60 billion, or about twice as much as the previous record.

In recent years there has been increasing exposure and vulnerability of the U.S. to extreme weather and climate events. To better reflect this we have integrated county and census tract socioeconomic vulnerability and exposure analysis to highlight U.S. counties where extremes may cause disproportionate physical, social and economic impacts on vulnerable populations (National Academies of Sciences, Engineering, and Medicine. Compounding Disasters in Gulf Coast Communities 2020-2021: Impacts, Findings, and Lessons (2024); Multi-Hazard Mitigation Council. Natural Hazard Mitigation Saves (2019); 4th and 5th U.S. National Climate Assessments (2017, 2023)). For example, see the new report: Hurricane Ida’s Impact On Socially Vulnerable Communities.

Billion-dollar weather and climate disaster events have affected every U.S. state since 1980 and each region faces a unique combination of recurring hazards. The two charts above highlight how the frequency of billion-dollar disasters differs across both time and space. The combined historical risk of U.S. severe storms and river flooding events places the spring and summer seasons in the high-risk category for simultaneous extreme weather and climate events.