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Natural hazard risk in Williamson County, Texas

Updated October 30, 2026. Based on FEMA, NOAA and OpenFEMA data. Published by Humblebee.

FEMA overall Risk Index rating: Relatively Moderate (score 90.1 of 100)[5]

Expected annual loss (FEMA)
$136.6 million[1]
Federal disaster declarations since 1974
23[2]
NFIP flood claims paid, 1978 to 2026
$22.3 million[3]
Tornadoes recorded, 1950 to 2024
74[4]

FEMA rates the overall natural hazard risk for Williamson County, Texas as Relatively Moderate, with a Risk Index score of 90.1 out of 100[5]. The hazards with the highest FEMA scores within the county are hail, winter weather and cold wave[6].

FEMA risk ratings for each hazard

Ratings and expected losses from the FEMA National Risk Index. Each rating compares this county with all US counties for that hazard, from Very Low to Very High. They are planning estimates, not predictions, and they do not describe any single property.

FEMA's National Risk Index rates hazards relative to all US counties[7]. FEMA estimates Expected Annual Loss from all 18 natural hazards at $136.6 million a year[1]. This is an estimate of average yearly loss, not money anyone paid. By FEMA's estimates, the largest losses come from inland flooding ($71.0 million a year), cold wave ($21.3 million a year) and tornado ($16.5 million a year)[8]. FEMA rates Social Vulnerability as Very Low[9]. FEMA describes this as how susceptible social groups are to the harm natural hazards cause[9]. FEMA rates Community Resilience as Very High, which it describes as a community's ability to prepare for, withstand and recover from hazards[10].

Hazards sorted by FEMA hazard-type Risk Index score, highest first
HazardFEMA risk ratingExpected annual loss
HailRelatively High$14.1 million[11]
Winter WeatherVery High$1.5 million[12]
Cold WaveRelatively High$21.3 million[13]
TornadoRelatively High$16.5 million[14]
Inland FloodingRelatively Moderate$71.0 million[15]
Heat WaveRelatively Moderate$5.3 million[16]
LightningRelatively High$1.8 million[17]
WildfireRelatively Low$1.6 million[18]
Ice StormRelatively Moderate$403,000[19]
DroughtRelatively Moderate$964,000[20]
HurricaneRelatively Low$860,000[21]
Strong WindRelatively Moderate$1.0 million[22]
EarthquakeVery Low$197,000[23]
LandslideVery Low$278[24]

Rated Not Applicable by FEMA for this county: avalanche, coastal flooding, tsunami, volcanic activity[25].

Social vulnerability and community resilience

FEMA uses these two ratings to scale expected losses into the Risk Index.

FEMA measureRatingScore
Social vulnerabilityVery Low10.6[9]
Community resilienceVery High87.9[10]

Flooding and flood insurance

FEMA rates inland flooding risk Relatively Moderate for Williamson County, with an Expected Annual Loss rating of Relatively High[15]. OpenFEMA lists 1,949 residential flood insurance contracts in force as of 2026-08-03[26]. Inside FEMA's mapped Special Flood Hazard Area, 45.8% of homes are insured[26]. OpenFEMA records 741 NFIP claims for losses from 1978 to 2026, and NFIP paid $22.3 million in total[3]. County ratings do not show the flood zone of one address, so FEMA's Flood Map Service Center is the place to look up an address[27].

Measure Value
Inland Flooding, FEMA risk rating[15] Relatively Moderate, $71.0 million expected loss a year
NFIP residential flood policies in force (2026)[26] 1,949 of 177,153 homes
Homes in FEMA's mapped high-risk flood area (SFHA)[26] 1,291, of which 591 insured
NFIP flood claims, 1978 to 2026[3] 741 filed, $22.3 million paid

Is a specific address in a flood zone? Only FEMA's flood maps answer that, property by property[27]. This page describes the whole county.

Search an address on the FEMA Flood Map Service Center

Disaster declarations and tornado records

OpenFEMA lists 23 federal disaster declarations for natural hazards that include Williamson County since 1974[2]. The most recent listed is DR-4879-TX for severe storms, straight-line winds and flooding, declared 2025-07-06[28]. NOAA's tornado database records 74 tornadoes touching the county from 1950 to 2024[4]. The most recent recorded tornado was on 2022-10-24[4].

Federal disaster declarations for natural hazards that include Williamson County, since 1974
Incident type Declarations
Fire[2] 8
Severe Storm[2] 4
Hurricane[2] 4
Flood[2] 3
Severe Ice Storm[2] 2
Winter Storm[2] 1
Drought[2] 1
Most recent declarations
Declaration Incident Declared
DR-4879-TX[28] Severe Storms, Straight-Line Winds, And Flooding 2025-07-06
DR-4705-TX[28] Severe Winter Storm 2023-04-21
DR-4586-TX[28] Severe Winter Storms 2021-02-19
EM-3554-TX[28] Severe Winter Storm 2021-02-14
DR-4223-TX[28] Severe Storms, Tornadoes, Straight-Line Winds And Flooding 2015-05-29

How to prepare

Steps from Ready.gov, FEMA's preparedness site, for the hazards with the highest FEMA ratings here. Follow instructions from local officials and the National Weather Service when a warning is issued.

Winter storms and cold

Before

  • Insulate your home and learn how to keep pipes from freezing.
  • Install and test smoke and carbon monoxide detectors with battery backup.
  • Keep several days of supplies in case the power goes out, including medication and pet needs.
  • Put an emergency kit in your car with jumper cables, sand, blankets, water and snacks, and keep the tank full.

During

  • Under a winter storm warning, find shelter right away.
  • Stay off the roads if you can. If you are stuck in your car, stay inside it.
  • Run generators and grills only outdoors, away from windows, and never heat your home with an oven or stove.

Source: Ready.gov, winter storms and cold

Tornadoes

Before

  • Learn the warning signs: a rotating funnel cloud, an approaching cloud of debris or a loud roar like a freight train.
  • Sign up for community warning systems and learn what your local sirens sound like.
  • Pick a safe spot, such as a safe room built to FEMA criteria or an ICC 500 storm shelter, and practice getting there.
  • Include your pets in the household emergency plan.
  • Keep supplies, food, water and medication in case you have to stay home for a long time.

During

  • Go right away to the safe place you picked in advance.
  • Protect your head and neck with your arms and stay away from windows, doors and outside walls.
  • No place in a car is fully safe. If you can get lower than the road, leave the car and lie down there.

Source: Ready.gov, tornadoes

Floods

Before

  • Check your flood risk with FEMA's Flood Map Service Center, and remember that floods do not follow map lines.
  • Sign up for your community's warning system. NOAA Weather Radio also broadcasts alerts.
  • Buy flood insurance through the NFIP well before a disaster. Homeowners policies do not cover flooding, and a new policy typically takes up to 30 days to go into effect.
  • Make a household plan with evacuation routes, shelter locations and what to do in a flash flood.
  • Keep important documents in a waterproof container and make password-protected digital copies.

During

  • If you are told to evacuate, leave right away and never drive around barricades.
  • Do not walk, swim or drive through floodwater. Six inches of moving water can knock you down.
  • If you are trapped in a building, go to the highest level, but do not climb into a closed attic.

Source: Ready.gov, floods

Questions people ask

Is Williamson County at risk of flooding?
FEMA rates inland flooding risk Relatively Moderate for Williamson County compared with other US counties[15]. FEMA's estimated Expected Annual Loss from inland flooding is $71.0 million a year[8].
Is Williamson County at risk of tornadoes?
FEMA rates tornado risk Relatively High compared with other US counties[14]. NOAA's tornado database records 74 tornadoes touching the county from 1950 to 2024[4].
Is Williamson County at risk of earthquakes or hurricanes?
FEMA rates earthquake risk Very Low[23] and hurricane risk Relatively Low[21] compared with other US counties.
How many disasters have been declared in Williamson County?
OpenFEMA lists 23 federal disaster declarations for natural hazards that include the county since 1974[2].
How do I check the flood zone of an address in Williamson County?
Look up the address in FEMA's Flood Map Service Center or ask the local floodplain manager[27].

Facts and sources

  1. FEMA National Risk Index (version 1.20, December 2025): Expected Annual Loss from all 18 natural hazards in Williamson County is $136.6 million a year (Expected Annual Loss rating Relatively Moderate, score 93.5). Of this, buildings account for $90.5 million, injuries and deaths (converted to dollars by FEMA) for... FEMA National Risk Index
  2. OpenFEMA Disaster Declarations Summaries list 23 federal disaster declarations for natural hazards that include Williamson County since 1974 (12 major disaster, 11 emergency or fire management). By incident type: fire 8, severe storm 4, hurricane 4, flood 3, severe ice storm 2, winter storm 1, drought 1. Biological... OpenFEMA Disaster Declarations
  3. HazardFacts tally of OpenFEMA NFIP Redacted Claims (losses from 1978 to 2026): 741 National Flood Insurance Program claims were filed for losses in Williamson County, 572 of them with a payment, and NFIP paid $22.3 million in total (building, contents and increased cost of compliance, in dollars of the year paid).... OpenFEMA NFIP claims
  4. NOAA Storm Prediction Center tornado database (1950 to 2024): 74 recorded tornadoes touched Williamson County. The strongest were rated F5 (most recent of them on 1997-05-27). 7 were rated F3/EF3 or stronger. The most recent recorded tornado was on 2022-10-24. Ratings used the Fujita scale until early 2007 and the... NOAA Storm Prediction Center
  5. FEMA National Risk Index (version 1.20, December 2025): the overall natural hazard Risk Index rating for Williamson County is Relatively Moderate, with a Risk Index score of 90.1 out of 100. The score is the county's percentile rank among all US counties. FEMA National Risk Index
  6. Among the 18 hazards in the FEMA National Risk Index (version 1.20, December 2025), the hazards with the highest hazard-type Risk Index scores for Williamson County are hail (98.6, Relatively High), winter weather (96.7, Very High), cold wave (95.9, Relatively High). HazardFacts sorted FEMA's published scores;... FEMA National Risk Index
  7. FEMA's National Risk Index FAQ (December 2025): Expected Annual Loss is FEMA's estimate of the average economic loss in dollars from natural hazards each year. The index is not meant to predict how much damage a community will have in the next year, and a hazard can still cause damage where a rating is low. Scores... FEMA National Risk Index documentation
  8. HazardFacts sorted FEMA's hazard-type Expected Annual Loss values for Williamson County (National Risk Index v1.20): the largest are inland flooding ($71.0 million a year), cold wave ($21.3 million a year), tornado ($16.5 million a year), out of $136.6 million a year from all 18 hazards. FEMA National Risk Index
  9. FEMA National Risk Index (version 1.20, December 2025): Social Vulnerability rating for Williamson County is Very Low (score 10.6). FEMA describes social vulnerability as how susceptible social groups are to the harm natural hazards cause. FEMA National Risk Index
  10. FEMA National Risk Index (version 1.20, December 2025): Community Resilience rating for Williamson County is Very High (score 87.9). FEMA describes community resilience as a community's ability to prepare for, withstand and recover from hazards. FEMA National Risk Index
  11. FEMA National Risk Index (version 1.20, December 2025), hail in Williamson County: Risk Index rating Relatively High (score 98.6 of 100). Expected Annual Loss $14.1 million a year (rating Relatively High). Annualized frequency 3.95 events per year, from recorded occurrences over a period of record of 37 years. FEMA National Risk Index
  12. FEMA National Risk Index (version 1.20, December 2025), winter weather in Williamson County: Risk Index rating Very High (score 96.7 of 100). Expected Annual Loss $1.5 million a year (rating Very High). Annualized frequency 3.74 events per year, from recorded occurrences over a period of record of 18 years. FEMA National Risk Index
  13. FEMA National Risk Index (version 1.20, December 2025), cold wave in Williamson County: Risk Index rating Relatively High (score 95.9 of 100). Expected Annual Loss $21.3 million a year (rating Very High). Annualized frequency 0.63 event-days per year, from recorded occurrences over a period of record of 18 years. FEMA National Risk Index
  14. FEMA National Risk Index (version 1.20, December 2025), tornado in Williamson County: Risk Index rating Relatively High (score 93.8 of 100). Expected Annual Loss $16.5 million a year (rating Relatively High). Annualized frequency 0.62 events per year, from recorded occurrences over a period of record of 38 years. FEMA National Risk Index
  15. FEMA National Risk Index (version 1.20, December 2025), inland flooding in Williamson County: Risk Index rating Relatively Moderate (score 91.3 of 100). Expected Annual Loss $71.0 million a year (rating Relatively High). Annualized frequency 3.64 event-days per year, from recorded occurrences over a period of... FEMA National Risk Index
  16. FEMA National Risk Index (version 1.20, December 2025), heat wave in Williamson County: Risk Index rating Relatively Moderate (score 91.0 of 100). Expected Annual Loss $5.3 million a year (rating Relatively Moderate). Annualized frequency 10 event-days per year, from recorded occurrences over a period of record of... FEMA National Risk Index
  17. FEMA National Risk Index (version 1.20, December 2025), lightning in Williamson County: Risk Index rating Relatively High (score 88.8 of 100). Expected Annual Loss $1.8 million a year (rating Relatively High). Annualized frequency 49.36 events per year, from recorded occurrences over a period of record of 24 years. FEMA National Risk Index
  18. FEMA National Risk Index (version 1.20, December 2025), wildfire in Williamson County: Risk Index rating Relatively Low (score 87.8 of 100). Expected Annual Loss $1.6 million a year (rating Relatively Moderate). FEMA's modeled annual frequency is 0.001 events per year. FEMA National Risk Index
  19. FEMA National Risk Index (version 1.20, December 2025), ice storm in Williamson County: Risk Index rating Relatively Moderate (score 72.4 of 100). Expected Annual Loss $403,000 a year (rating Relatively Moderate). Annualized frequency 0.65 event-days per year, from recorded occurrences over a period of record of 68... FEMA National Risk Index
  20. FEMA National Risk Index (version 1.20, December 2025), drought in Williamson County: Risk Index rating Relatively Moderate (score 72.3 of 100). Expected Annual Loss $964,000 a year (rating Relatively Moderate). Annualized frequency 59.3 event-days per year, from recorded occurrences over a period of record of 22... FEMA National Risk Index
  21. FEMA National Risk Index (version 1.20, December 2025), hurricane in Williamson County: Risk Index rating Relatively Low (score 69.0 of 100). Expected Annual Loss $860,000 a year (rating Relatively Low). Annualized frequency 0.04 events per year, from recorded occurrences over a period of record of 172 years for... FEMA National Risk Index
  22. FEMA National Risk Index (version 1.20, December 2025), strong wind in Williamson County: Risk Index rating Relatively Moderate (score 55.9 of 100). Expected Annual Loss $1.0 million a year (rating Relatively Moderate). Annualized frequency 1.72 events per year, from recorded occurrences over a period of record of... FEMA National Risk Index
  23. FEMA National Risk Index (version 1.20, December 2025), earthquake in Williamson County: Risk Index rating Very Low (score 36.4 of 100). Expected Annual Loss $197,000 a year (rating Very Low). FEMA's modeled annual frequency is 0.0005 events per year. FEMA National Risk Index
  24. FEMA National Risk Index (version 1.20, December 2025), landslide in Williamson County: Risk Index rating Very Low (score 24.0 of 100). Expected Annual Loss $278 a year (rating Very Low). FEMA National Risk Index
  25. FEMA National Risk Index (version 1.20, December 2025) rates these hazards Not Applicable for Williamson County: avalanche, coastal flooding, tsunami, volcanic activity. FEMA uses Not Applicable when its source data has no historical record of the hazard in the community and the hazard is not considered... FEMA National Risk Index documentation
  26. NFIP Residential Penetration Rates (OpenFEMA, as of 2026-08-03): 1,949 residential flood insurance contracts were in force in Williamson County, out of 177,153 residential structures, a penetration rate of 1.1%. Inside FEMA's mapped Special Flood Hazard Area there were 1,291 residential structures and 591... OpenFEMA NFIP penetration rates
  27. FEMA's Flood Map Service Center is the official public source for flood maps (Flood Insurance Rate Maps) produced under the National Flood Insurance Program. Flood zones apply to specific properties: look up an address there or ask the local floodplain manager. County-level ratings do not tell you the flood zone of... FEMA Flood Map Service Center
  28. Most recent federal disaster declarations for natural hazards (table on this page). OpenFEMA Disaster Declarations

FEMA's National Risk Index compares each county with all other US counties. Ratings are relative (Very Low to Very High), not a measure of safety. Never call a place safe, unsafe, good or bad to live in. Risk Index and Expected Annual Loss values are FEMA estimates for planning. They do not predict next year's losses and do not apply to a single property. Flood zones are set by FEMA flood maps for specific properties. County ratings and flood insurance counts do not tell anyone whether an address is in a flood zone. Disaster declaration, NFIP and tornado counts are records of the past for this county only. Do not compare with other counties unless a fact does.

Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties, v1.20 (December 2025). Retrieved from fema.maps.arcgis.com on October 30, 2026. This product uses the Federal Emergency Management Agency's National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s). This product uses the FEMA OpenFEMA API, but is not endorsed by FEMA.