741 flood insurance claims·$22.2M paid·4 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Williamson County, Texas. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding from thunderstorms dominates the flood risk in Williamson County, supported by NOAA data recording 153 flash flood events and 5 deaths over the last 30 years, compared to 7 general flood events.
Heavy rainfall and atmospheric conditions drive these severe events, such as the excessive rainfall and flash flooding observed in July 2025. During this period, near-record precipitable water values and mid-level circulation generated efficient rain-making storms across the region.
Homeowners and real estate agents should note that flood claims occur across multiple zones, with the highest concentrations in designated high-risk and moderate-to-low risk areas. Specifically, Zone A accounts for 361 claims with an average water depth of 9 inches and an average payout of $47,230, while Zone X records 202 claims with an average water depth of 8 inches and an average payout of $48,635. Properties in unknown or lesser-documented zones also show history, including 165 claims in Zone UNKNOWN averaging 1 inch of water depth and a $10,232 payout. Properties located in Zone A and Zone X, as well as unmapped areas, require the closest attention based on historical claim frequencies and payout averages.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
3% of Williamson County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
373 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 7 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 2010, with 210 claims and $10.7M paid.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
33 NOAA storm reports from Williamson County describe what happened, in the words of the forecasters who covered it. Read the Texas flood stories →
26 federal disaster declarations since 1974, 4 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms, Straight-line Winds, And Flooding | Jul 2, 2025 |
| Severe Winter Storm | Jan 30, 2023 |
| Severe Winter Storm | Feb 11, 2021 |
| Severe Winter Storms | Feb 11, 2021 |
| Severe Storms, Tornadoes, Straight-line Winds And Flooding | May 4, 2015 |
| Moonglow Fire | Sep 5, 2011 |
| Wildfires | Aug 30, 2011 |
| Horseshoe Fire | Aug 15, 2011 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
160 since 1996: 153 flash floods and 7 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | May 6, 2025 | — |
| Flash Flood | Jul 5, 2025 | — |
| Flash Flood | Jul 5, 2025 | $25.0M |
| Flash Flood | Apr 20, 2023 | — |
| Flash Flood | Aug 27, 2022 | — |
| Flash Flood | May 1, 2021 | — |
| Flood | Jun 23, 2020 | — |
| Flash Flood | Apr 6, 2019 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · May 6, 2025. Thunderstorms developed along a cold front as it moved through South-Central Texas. Some of these storms produced large hail and heavy rain that led to flash flooding.
Flash Flood · Jul 5, 2025. Precipitable water values over South-Central Texas remained near record levels, and a mid-level anticyclonic circulation continued over Central Texas providing lift to generate thunderstorms. These storms were efficient rain making storms leading to another night of excessive rainfall. Parts of Burnet and Travis Counties received 12-16 inches of rain in approximately six hours that led to deadly flash flooding. Ei…
Flash Flood · Apr 20, 2023. An upper level trough moved across the southwest US and brought a cold front through Central Texas. Thunderstorms developed in the warm, moist airmass south of the front in response to a mid-level shortwave trough. Some of these storms produced severe weather including one tornado.
Flash Flood · Aug 27, 2022. Thunderstorms developed along a stationary front and one of these storms produced heavy rain that led to flash flooding.
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Williamson County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.