Increasing Volatility of Extreme Daily Precipitation Across the Contiguous United States.
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| Title: | Increasing Volatility of Extreme Daily Precipitation Across the Contiguous United States. |
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| Authors: | Sarhadi, Ali1 (AUTHOR) sarhadi@gatech.edu, Modarres, Reza2 (AUTHOR) |
| Source: | Journal of Climate. Jun2026, Vol. 39 Issue 12, p1-16. 16p. |
| Subjects: | Precipitation variability, Flood risk, Precipitation anomalies, Climate change, GARCH model, Meteorological precipitation, Geography |
| Abstract: | Understanding changes in the volatility of extreme precipitation—defined as the day-to-day instability of rainfall, including how strongly it fluctuates and how long those fluctuations persist—is essential for assessing hydroclimatic risks and developing effective adaptation strategies in a warming climate. We present a continental-scale analysis of day-to-day volatility in maximum daily precipitation across the Contiguous United States (CONUS) from 1950–2022. Volatility is estimated using a Generalized Autoregressive Conditional Heteroskedasticity (GARCH) model, which captures both short- and long-term memory in daily precipitation variability. Our results reveal that annual maximum daily precipitation volatility has increased by 37.3 mm—an approximate increase of 8.4% since 1950—across CONUS. Distinct regional patterns emerge, with the largest increases in volatility observed in the South (17.2%), Atlantic East (7.5%), Midwest (11.3%) and Western Territories (6.7%), while the West Pacific shows a slight decline (-0.4%). High-volatility days—those exceeding the 95th percentile of volatility—have become 20.8% more frequent, with a statistically significant regime shift occurring around 1978 (± 2 years). Trends are strongest in the upper tail (95th percentile) of the volatility distribution, indicating that extreme precipitation events are becoming more unstable, even as typical events remain relatively unchanged. These shifts in precipitation volatility reflect a growing tendency for abrupt transitions between wet and dry days. Such instability elevates flash-flood risk, challenges infrastructure design, and increases socio-economic vulnerability. Targeted adaptation strategies will therefore be essential to address the impacts of increasing precipitation volatility in a changing climate. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Understanding changes in the volatility of extreme precipitation—defined as the day-to-day instability of rainfall, including how strongly it fluctuates and how long those fluctuations persist—is essential for assessing hydroclimatic risks and developing effective adaptation strategies in a warming climate. We present a continental-scale analysis of day-to-day volatility in maximum daily precipitation across the Contiguous United States (CONUS) from 1950–2022. Volatility is estimated using a Generalized Autoregressive Conditional Heteroskedasticity (GARCH) model, which captures both short- and long-term memory in daily precipitation variability. Our results reveal that annual maximum daily precipitation volatility has increased by 37.3 mm—an approximate increase of 8.4% since 1950—across CONUS. Distinct regional patterns emerge, with the largest increases in volatility observed in the South (17.2%), Atlantic East (7.5%), Midwest (11.3%) and Western Territories (6.7%), while the West Pacific shows a slight decline (-0.4%). High-volatility days—those exceeding the 95th percentile of volatility—have become 20.8% more frequent, with a statistically significant regime shift occurring around 1978 (± 2 years). Trends are strongest in the upper tail (95th percentile) of the volatility distribution, indicating that extreme precipitation events are becoming more unstable, even as typical events remain relatively unchanged. These shifts in precipitation volatility reflect a growing tendency for abrupt transitions between wet and dry days. Such instability elevates flash-flood risk, challenges infrastructure design, and increases socio-economic vulnerability. Targeted adaptation strategies will therefore be essential to address the impacts of increasing precipitation volatility in a changing climate. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 08948755 |
| DOI: | 10.1175/JCLI-D-25-0056.1 |
