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Natural hazard risk in Williamson County, Tennessee

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

FEMA overall Risk Index rating: Relatively Moderate (score 85.1 of 100)[5]

Expected annual loss (FEMA)
$98.0 million[1]
Federal disaster declarations since 1974
14[2]
NFIP flood claims paid, 1978 to 2026
$31.1 million[3]
Tornadoes recorded, 1950 to 2024
25[4]

FEMA rates the overall natural hazard risk for Williamson County Relatively Moderate, with a Risk Index score of 85.1 out of 100[5]. FEMA's National Risk Index gives the highest hazard scores within this county to cold wave, earthquake and strong wind[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 (version 1.20, December 2025) estimates Expected Annual Loss from all 18 natural hazards at $98.0 million a year[1]. This is a FEMA estimate of average yearly loss, not money anyone paid[7]. By Expected Annual Loss, the largest hazards are inland flooding ($57.0 million a year), cold wave ($13.4 million a year) and tornado ($11.6 million a year)[8]. FEMA rates social vulnerability Very Low compared with other US counties[9]. FEMA rates community resilience Very High[10]. The index does not predict next year's losses[7].

Hazards sorted by FEMA hazard-type Risk Index score, highest first
HazardFEMA risk ratingExpected annual loss
Cold WaveRelatively High$13.4 million[11]
EarthquakeRelatively Low$8.5 million[12]
Strong WindRelatively High$3.4 million[13]
TornadoRelatively Moderate$11.6 million[14]
Inland FloodingRelatively Moderate$57.0 million[15]
Winter WeatherRelatively Moderate$469,000[16]
Ice StormRelatively High$1.0 million[17]
Heat WaveRelatively Low$1.8 million[18]
LandslideVery Low$3,157[19]
LightningRelatively Low$468,000[20]
HailRelatively Low$332,000[21]
HurricaneVery Low$55,000[22]
WildfireVery Low$45,000[23]
DroughtRelatively Low$77,000[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 High95.2[10]

Flooding and flood insurance

FEMA rates inland flooding risk Relatively Moderate for Williamson County, with an Expected Annual Loss of $57.0 million a year[15]. OpenFEMA lists 1,284 residential flood insurance contracts in force, a penetration rate of 2.4%[26]. OpenFEMA lists 86.3% of homes inside the SFHA as insured, meaning 687 contracts for 796 residential structures in FEMA's mapped Special Flood Hazard Area[26]. OpenFEMA NFIP claims data lists 1,103 claims for losses from 1978 to 2026, and NFIP paid $31.1 million in total[3]. To check an address, use FEMA's Flood Map Service Center[27].

Measure Value
Inland Flooding, FEMA risk rating[15] Relatively Moderate, $57.0 million expected loss a year
NFIP residential flood policies in force (2026)[26] 1,284 of 53,519 homes
Homes in FEMA's mapped high-risk flood area (SFHA)[26] 796, of which 687 insured
NFIP flood claims, 1978 to 2026[3] 1,103 filed, $31.1 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 14 federal disaster declarations for natural hazards that include Williamson County since 1974[2]. The most recent listed is DR-4898-TN, Severe Winter Storm, declared 2026-02-06[28]. NOAA's tornado database records 25 tornadoes touching the county from 1950 to 2024[4]. The most recent recorded tornado was on 2023-08-12[4].

Federal disaster declarations for natural hazards that include Williamson County, since 1974
Incident type Declarations
Severe Storm[2] 8
Winter Storm[2] 2
Tornado[2] 2
Hurricane[2] 1
Flood[2] 1
Most recent declarations
Declaration Incident Declared
DR-4898-TN[28] Severe Winter Storm 2026-02-06
EM-3635-TN[28] Severe Winter Storm 2026-01-24
EM-3625-TN[28] Severe Storms, Straight-Line Winds, Tornadoes, And Flooding 2025-04-02
DR-4601-TN[28] Severe Storms, Tornadoes, And Flooding 2021-05-08
DR-1909-TN[28] Severe Storms, Flooding, Straight-Line Winds, And Tornadoes 2010-05-04

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

Earthquakes

Before

  • Practice Drop, Cover, and Hold On with your family and coworkers.
  • Sign up for earthquake alerts that can warn you before shaking starts.
  • Make a plan with an out-of-state contact and a place to meet if you get separated.
  • Anchor heavy items such as bookcases, refrigerators and water heaters, and keep heavy things on low shelves.
  • Consider earthquake insurance. Standard homeowners policies do not cover earthquake damage.

During

  • Drop to your hands and knees, cover your head and neck, and hold on until the shaking stops.
  • Indoors, stay where you are and avoid doorways. Outdoors, move to an open area away from buildings and power lines.
  • If you are driving, pull over, stop and set the parking brake.

Source: Ready.gov, earthquakes

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

Questions people ask

Is Williamson County at risk of flooding?
FEMA rates inland flooding risk Relatively Moderate compared with other US counties[15]. Inland flooding makes up the largest share of expected annual loss by FEMA's estimate[8].
Does Williamson County get tornadoes?
NOAA's tornado database records 25 tornadoes that touched the county from 1950 to 2024[4]. FEMA rates tornado risk Relatively Moderate compared with other US counties[14].
How many disasters have been declared in Williamson County?
OpenFEMA lists 14 federal disaster declarations for natural hazards that include the county since 1974[2].
How do I check my flood zone?
Look up the address in FEMA's Flood Map Service Center or ask the local floodplain manager[27]. County-level ratings do not give the flood zone of one address[27].
Is Williamson County at risk of wildfire?
FEMA rates wildfire risk Very Low compared with other US counties[23].

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 $98.0 million a year (Expected Annual Loss rating Relatively Moderate, score 90.5). Of this, buildings account for $71.1 million, injuries and deaths (converted to dollars by FEMA) for... FEMA National Risk Index
  2. OpenFEMA Disaster Declarations Summaries list 14 federal disaster declarations for natural hazards that include Williamson County since 1974 (11 major disaster, 3 emergency or fire management). By incident type: severe storm 8, winter storm 2, tornado 2, hurricane 1, flood 1. Biological (such as COVID-19) and other... OpenFEMA Disaster Declarations
  3. HazardFacts tally of OpenFEMA NFIP Redacted Claims (losses from 1978 to 2026): 1,103 National Flood Insurance Program claims were filed for losses in Williamson County, 936 of them with a payment, and NFIP paid $31.1 million in total (building, contents and increased cost of compliance, in dollars of the year... OpenFEMA NFIP claims
  4. NOAA Storm Prediction Center tornado database (1950 to 2024): 25 recorded tornadoes touched Williamson County. The strongest were rated F4 (most recent of them on 1988-12-24). 3 were rated F3/EF3 or stronger. The most recent recorded tornado was on 2023-08-12. 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 85.1 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 cold wave (90.7, Relatively High), earthquake (89.4, Relatively Low), strong wind (89.1, Relatively High). HazardFacts sorted FEMA's published... 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 ($57.0 million a year), cold wave ($13.4 million a year), tornado ($11.6 million a year), out of $98.0 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 95.2). 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), cold wave in Williamson County: Risk Index rating Relatively High (score 90.7 of 100). Expected Annual Loss $13.4 million a year (rating Relatively High). Annualized frequency 1.16 event-days per year, from recorded occurrences over a period of record of 18... FEMA National Risk Index
  12. FEMA National Risk Index (version 1.20, December 2025), earthquake in Williamson County: Risk Index rating Relatively Low (score 89.4 of 100). Expected Annual Loss $8.5 million a year (rating Relatively Moderate). FEMA's modeled annual frequency is 0.0034 events per year. FEMA National Risk Index
  13. FEMA National Risk Index (version 1.20, December 2025), strong wind in Williamson County: Risk Index rating Relatively High (score 89.1 of 100). Expected Annual Loss $3.4 million a year (rating Relatively High). Annualized frequency 6.11 events per year, from recorded occurrences over a period of record of 38 years. FEMA National Risk Index
  14. FEMA National Risk Index (version 1.20, December 2025), tornado in Williamson County: Risk Index rating Relatively Moderate (score 88.8 of 100). Expected Annual Loss $11.6 million a year (rating Relatively High). Annualized frequency 0.51 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 88.2 of 100). Expected Annual Loss $57.0 million a year (rating Relatively Moderate). Annualized frequency 2.18 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), winter weather in Williamson County: Risk Index rating Relatively Moderate (score 84.6 of 100). Expected Annual Loss $469,000 a year (rating Relatively High). Annualized frequency 5.16 events per year, from recorded occurrences over a period of record of 18... FEMA National Risk Index
  17. FEMA National Risk Index (version 1.20, December 2025), ice storm in Williamson County: Risk Index rating Relatively High (score 84.4 of 100). Expected Annual Loss $1.0 million a year (rating Relatively High). Annualized frequency 0.62 event-days per year, from recorded occurrences over a period of record of 68 years. FEMA National Risk Index
  18. FEMA National Risk Index (version 1.20, December 2025), heat wave in Williamson County: Risk Index rating Relatively Low (score 72.5 of 100). Expected Annual Loss $1.8 million a year (rating Relatively Moderate). Annualized frequency 4.95 event-days per year, from recorded occurrences over a period of record of 18... FEMA National Risk Index
  19. FEMA National Risk Index (version 1.20, December 2025), landslide in Williamson County: Risk Index rating Very Low (score 54.2 of 100). Expected Annual Loss $3,157 a year (rating Very Low). FEMA National Risk Index
  20. FEMA National Risk Index (version 1.20, December 2025), lightning in Williamson County: Risk Index rating Relatively Low (score 53.7 of 100). Expected Annual Loss $468,000 a year (rating Relatively Moderate). Annualized frequency 60.55 events per year, from recorded occurrences over a period of record of 24 years. FEMA National Risk Index
  21. FEMA National Risk Index (version 1.20, December 2025), hail in Williamson County: Risk Index rating Relatively Low (score 41.8 of 100). Expected Annual Loss $332,000 a year (rating Relatively Low). Annualized frequency 3.5 events per year, from recorded occurrences over a period of record of 37 years. FEMA National Risk Index
  22. FEMA National Risk Index (version 1.20, December 2025), hurricane in Williamson County: Risk Index rating Very Low (score 41.0 of 100). Expected Annual Loss $55,000 a year (rating Very Low). Annualized frequency 0.02 events per year, from recorded occurrences over a period of record of 172 years for the Atlantic... FEMA National Risk Index
  23. FEMA National Risk Index (version 1.20, December 2025), wildfire in Williamson County: Risk Index rating Very Low (score 39.7 of 100). Expected Annual Loss $45,000 a year (rating Very Low). FEMA's modeled annual frequency is 0 events per year. FEMA National Risk Index
  24. FEMA National Risk Index (version 1.20, December 2025), drought in Williamson County: Risk Index rating Relatively Low (score 35.7 of 100). Expected Annual Loss $77,000 a year (rating Relatively Low). Annualized frequency 9.57 event-days per year, from recorded occurrences over a period of record of 22 years. 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): 1,284 residential flood insurance contracts were in force in Williamson County, out of 53,519 residential structures, a penetration rate of 2.4%. Inside FEMA's mapped Special Flood Hazard Area there were 796 residential structures and 687 contracts, a... 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.