The catastrophic flooding in Central Texas on 4-5 July 2025, resulted from a combination of meteorological factors that converged to produce an extreme rainfall event. Below is a summary of the main reasons for the heavy rainfall and subsequent flooding.
Remnant Circulation of Tropical Storm Barry: The remnants of Tropical Storm Barry, which, after dissipating, left a mid-level circulation that interacted with a trough over Texas. This interaction enhanced atmospheric instability, creating conditions conducive to heavy rainfall with intense thunderstorms.
Tropical Moisture Influx: A significant influx of tropical moisture from the east Pacific combined with the remnant circulation of Barry. This moisture-rich air mass fuelled the development of intense, slow-moving storms, leading to prolonged and heavy precipitation over Central Texas.
Slow-Moving Storm System: The storm system responsible for the rainfall was nearly stationary, causing repeated heavy showers over the same areas, particularly the Hill Country. Rainfall rates of 2–3 inches (50-75mm) per hour, with some areas receiving 5–11 inches (125-280mm) in a few hours overwhelmed local rivers and creeks.
In Hunt, Kerr County, near the Guadalupe River approximately 6.5 inches (165 mm) fell in just three hours from midnight during the early morning of 4 July. While in Kerrville, up to 10–11 inches (250-280mm) fell overnight with some reports indicating as much as 15 inches (380mm) in parts of the county.
The Kerrville area is known as “Flash Flood Alley”. The name being given idue to the region’s susceptibility to flash flooding, particularly in the Hill Country, where intense rainstorms are common and the shallow soil and steep terrain cause water to flow rapidly into rivers and tributaries. The heavy rain falling on the steep slopes and saturated soils led to rapid rises in river levels, with the Guadalupe River surging 22–29 feet (6.7-8.8 metres) in hours causing devastating flooding and a tragic set of outcomes.
