Extreme Heat

Hazard in Severe Weather

A silent, multi-day health hazard that stresses power grids and kills more people than any other weather event, mostly out of sight.

Plans also call it: heat wave, excessive heat, urban heat island

Talk to us about Extreme HeatAll 73 hazards →

What you’d hand your council

The first page of a Extreme Heat evidence brief: likelihood, impact and readiness on your own scale, every figure sourced.

Evidence brief for Cedar Ridge County (example)

September 14, 2026

Extreme Heat

Hazard in Severe Weather, on the established threats & hazards list

Impact
5432112345

Likelihood

Likelihood
3

Possible — Expected occasionally — roughly once in 10 to 50 years (2–10% chance in any year).

Impact
4

Major — Severe effects — casualties possible, serious damage across a significant share of the jurisdiction, essential services disrupted for weeks, outside assistance needed.

Readiness
3

Moderate — The organization has a generally established capability to manage this threat or hazard, but identifiable gaps remain. The organization could likely perform many required actions, though effectiveness may vary depending on conditions, staffing, resources, or complexity.

  • 2source documents
  • 58verified mentions
  • —federal declarations
  • 91.6NRI score, relatively high
Worked example: Cedar Ridge County is fictional. The scores illustrate the format and are nobody's decision. Open a full sample brief →

The national record

FEMA National Risk Index: Heat Wave

$7.1B
expected loss a year, nationally
109
counties rated high or very high

Your county’s own rating is the first thing we pull.

How it maps

The same hazard in the vocabularies your plan and FEMA already use.

FEMA National Risk Index
Heat Wave (HWAV)one of the 18 hazards NRI scores per county
FEMA declaration incident type
Not covered
NOAA Storm Events type
Heat, Excessive Heat
Hazzard category
Severe Weather, natural hazards

The national record

What the federal data says about Extreme Heat

The same national sources a Hazzard brief starts from. For your jurisdiction we narrow each one to your county and its neighbors.

Where Extreme Heat is rated high

Share of each state's counties FEMA rates Relatively High or Very High

Alabama: 2 of 67 counties rated high (3%) · $91M expected loss a yearAlaska: not rated for Extreme HeatArizona: 7 of 15 counties rated high (47%) · $1.2B expected loss a yearArkansas: 1 of 75 counties rated high (1%) · $145M expected loss a yearCalifornia: 17 of 58 counties rated high (29%) · $378M expected loss a yearColorado: 0 of 52 counties rated high (0%) · $13M expected loss a yearConnecticut: 0 of 9 counties rated high (0%) · $18M expected loss a yearDelaware: 0 of 3 counties rated high (0%) · $12M expected loss a yearDistrict of Columbia: 1 of 1 counties rated high (100%) · $40M expected loss a yearFlorida: 5 of 67 counties rated high (7%) · $165M expected loss a yearGeorgia: 0 of 159 counties rated high (0%) · $97M expected loss a yearHawaii: not rated for Extreme HeatIdaho: 0 of 44 counties rated high (0%) · $33M expected loss a yearIllinois: 3 of 102 counties rated high (3%) · $359M expected loss a yearIndiana: 1 of 92 counties rated high (1%) · $75M expected loss a yearIowa: 1 of 99 counties rated high (1%) · $61M expected loss a yearKansas: 3 of 105 counties rated high (3%) · $105M expected loss a yearKentucky: 2 of 120 counties rated high (2%) · $68M expected loss a yearLouisiana: 6 of 64 counties rated high (9%) · $140M expected loss a yearMaine: 0 of 16 counties rated high (0%) · $3M expected loss a yearMaryland: 4 of 24 counties rated high (17%) · $140M expected loss a yearMassachusetts: 1 of 13 counties rated high (8%) · $38M expected loss a yearMichigan: 2 of 83 counties rated high (2%) · $81M expected loss a yearMinnesota: 2 of 87 counties rated high (2%) · $103M expected loss a yearMississippi: 1 of 82 counties rated high (1%) · $87M expected loss a yearMissouri: 5 of 115 counties rated high (4%) · $711M expected loss a yearMontana: 0 of 56 counties rated high (0%) · $7M expected loss a yearNebraska: 1 of 93 counties rated high (1%) · $32M expected loss a yearNevada: 2 of 17 counties rated high (12%) · $305M expected loss a yearNew Hampshire: 0 of 10 counties rated high (0%) · $6M expected loss a yearNew Jersey: 5 of 21 counties rated high (24%) · $147M expected loss a yearNew Mexico: 0 of 33 counties rated high (0%) · $23M expected loss a yearNew York: 5 of 62 counties rated high (8%) · $270M expected loss a yearNorth Carolina: 1 of 89 counties rated high (1%) · $94M expected loss a yearNorth Dakota: 0 of 53 counties rated high (0%) · $3M expected loss a yearOhio: 3 of 88 counties rated high (3%) · $119M expected loss a yearOklahoma: 3 of 77 counties rated high (4%) · $241M expected loss a yearOregon: 2 of 36 counties rated high (6%) · $71M expected loss a yearPennsylvania: 3 of 67 counties rated high (4%) · $365M expected loss a yearRhode Island: 1 of 5 counties rated high (20%) · $10M expected loss a yearSouth Carolina: 0 of 46 counties rated high (0%) · $54M expected loss a yearSouth Dakota: 0 of 66 counties rated high (0%) · $10M expected loss a yearTennessee: 1 of 94 counties rated high (1%) · $95M expected loss a yearTexas: 13 of 254 counties rated high (5%) · $797M expected loss a yearUtah: 0 of 28 counties rated high (0%) · $34M expected loss a yearVermont: 0 of 14 counties rated high (0%) · $6M expected loss a yearVirginia: 1 of 118 counties rated high (1%) · $84M expected loss a yearWashington: 3 of 39 counties rated high (8%) · $99M expected loss a yearWest Virginia: 0 of 54 counties rated high (0%) · $19M expected loss a yearWisconsin: 1 of 72 counties rated high (1%) · $89M expected loss a yearWyoming: 0 of 18 counties rated high (0%) · $471K expected loss a year
  • None
  • Up to 10%
  • 10–25%
  • 25–50%
  • Over 50%
  • Not rated
FEMA National Risk Index v1.20.0, county table

In your plan

What a Extreme Heat profile needs, and where each part comes from

A local hazard mitigation plan profiles each hazard the same way (44 CFR 201.6). Here is how Hazzard fills each part for Extreme Heat.

  1. Location

    44 CFR 201.6(c)(2)(i)

    National data

    FEMA's National Risk Index rates Extreme Heat for every county. We place yours against its neighbors and the state, then add what your plans map in more detail.

  2. Extent

    44 CFR 201.6(c)(2)(i)

    Your documents

    The magnitude your plans use for Extreme Heat (a scale, a depth, an acreage, a duration), read from your documents and cited, so the profile states the strength you plan for.

  3. Previous occurrences

    44 CFR 201.6(c)(2)(i)

    Your documents

    FEMA files no declaration type for Extreme Heat. The history comes from your after-action reports, incident records and plans.

  4. Probability of future events

    44 CFR 201.6(c)(2)(i)

    National data

    NRI's annualized frequency for your county, and the declaration history, drafted into a likelihood on your own scale for your team to accept or change.

  5. Vulnerability and impacts

    44 CFR 201.6(c)(2)(ii)

    National data

    NRI's expected annual loss and social vulnerability for your county, the Census population profile and HHS emPOWER counts, with the impacts your plans already describe.

  6. The assessment itself

    Your team decides

    Likelihood, impact and readiness for Extreme Heat are drafted with every source attached, and a person on your team accepts each one. Hazzard never records a score on its own.

How we can help

How we’d help you prepare for Extreme Heat

  1. 1

    We pull your county's record

    FEMA's National Risk Index rating and expected loss, every disaster declaration, and the daily temperature record behind heat and cold, before we meet.

  2. 2

    We read the plans you already have

    Your hazard mitigation plan and EOP annexes, so you can see what they say about Extreme Heat and where the profile stops short.

  3. 3

    You leave with a cited brief

    Likelihood, impact and readiness for Extreme Heat on your own scale, every figure tied to its source, ready for the planning team or the council.

Also in Severe Weather

Preparing for Extreme Heat

Walk into your next plan update with Extreme Heat already sourced.

Severe weather is the part of a plan everyone assumes is covered. We check whether yours says why, with your county's own record instead of a regional average. A person replies within one business day.

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