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Extreme Temperatures

Hazard in Weather Hazards

A multi-day health and infrastructure hazard at both ends of the thermometer, where heat and cold kill quietly and strain the grid at its peak.

Includes: Extreme Cold, Extreme Heat

  • Extreme Cold. A slow-building health and infrastructure hazard, hypothermia, frozen pipes and heating failures that hit vulnerable residents first.
  • Extreme Heat. A silent, multi-day health hazard that stresses power grids and kills more people than any other weather event, mostly out of sight.
See a sample briefBook a walkthroughAll 31 hazards →

Sample brief

The first page of a Extreme Temperatures brief: likelihood, impact and readiness on your own scale, with each figure sourced.

Evidence brief for Cedar Ridge County (example)

September 14, 2026

Extreme Temperatures

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

Impact
5432112345

Likelihood

Likelihood
4

Likely — Expected within the decade — roughly once in 1 to 10 years (10–100% chance in any year).

Impact
3

Moderate — Notable effects — injuries possible, damage in multiple areas, essential services disrupted for days.

Readiness
2

Low — Some elements of capability are in place, but important gaps remain that could significantly limit the organization's ability to perform effectively. Additional development is needed before the capability can be relied upon.

  • 2source documents
  • 58verified mentions
  • 2federal 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: Cold Wave, Heat Wave

$17.0B
expected loss a year, nationally, across 2 NRI hazards
341
counties rated high or very high for Cold Wave

NRI scores Extreme Temperatures as 2 hazards, so the loss is summed and the county count is Cold Wave's, the larger of them. 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
Cold Wave (CWAV), Heat Wave (HWAV)2 of the 18 hazards NRI scores per county: Cold Wave $9.9B, 341 counties high; Heat Wave $7.1B, 109 counties high. The headline loss sums them; the county count is Cold Wave's
FEMA declaration incident type
Freezing18 declarations on record
NOAA Storm Events type
Cold/Wind Chill, Extreme Cold/Wind Chill, Frost/Freeze, Heat, Excessive Heat
Hazzard category
Weather Hazards, natural hazardsincludes Extreme Cold, Extreme Heat

The national record

What the federal data says about Extreme Temperatures

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

NRI scores Extreme Temperatures as 2 hazards: Cold Wave (CWAV), Heat Wave (HWAV). The map is the Cold Wave rating, the larger by expected loss; the others are in the crosswalk above.

Where Cold Wave is rated high

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

Alabama: 6 of 67 counties rated high (9%) · $153M expected loss a yearAlaska: 7 of 27 counties rated high (26%) · $80M expected loss a yearArizona: 0 of 11 counties rated high (0%) · $5M expected loss a yearArkansas: 1 of 75 counties rated high (1%) · $76M expected loss a yearCalifornia: 0 of 13 counties rated high (0%) · $705K expected loss a yearColorado: 6 of 63 counties rated high (10%) · $129M expected loss a yearConnecticut: 1 of 9 counties rated high (11%) · $23M expected loss a yearDelaware: 3 of 3 counties rated high (100%) · $38M expected loss a yearDistrict of Columbia: 1 of 1 counties rated high (100%) · $11M expected loss a yearFlorida: 10 of 67 counties rated high (15%) · $336M expected loss a yearGeorgia: 6 of 159 counties rated high (4%) · $213M expected loss a yearHawaii: 0 of 1 counties rated high (0%) · $0K expected loss a yearIdaho: 1 of 44 counties rated high (2%) · $63M expected loss a yearIllinois: 26 of 102 counties rated high (25%) · $1.4B expected loss a yearIndiana: 7 of 92 counties rated high (8%) · $255M expected loss a yearIowa: 2 of 99 counties rated high (2%) · $164M expected loss a yearKansas: 4 of 105 counties rated high (4%) · $199M expected loss a yearKentucky: 5 of 120 counties rated high (4%) · $169M expected loss a yearLouisiana: 12 of 64 counties rated high (19%) · $185M expected loss a yearMaine: 3 of 16 counties rated high (19%) · $47M expected loss a yearMaryland: 2 of 24 counties rated high (8%) · $50M expected loss a yearMassachusetts: 3 of 14 counties rated high (21%) · $49M expected loss a yearMichigan: 16 of 83 counties rated high (19%) · $448M expected loss a yearMinnesota: 12 of 87 counties rated high (14%) · $471M expected loss a yearMississippi: 9 of 82 counties rated high (11%) · $150M expected loss a yearMissouri: 8 of 115 counties rated high (7%) · $321M expected loss a yearMontana: 13 of 56 counties rated high (23%) · $244M expected loss a yearNebraska: 1 of 93 counties rated high (1%) · $74M expected loss a yearNevada: 0 of 13 counties rated high (0%) · $1M expected loss a yearNew Hampshire: 0 of 10 counties rated high (0%) · $16M expected loss a yearNew Jersey: 9 of 21 counties rated high (43%) · $136M expected loss a yearNew Mexico: 0 of 33 counties rated high (0%) · $21M expected loss a yearNew York: 11 of 62 counties rated high (18%) · $310M expected loss a yearNorth Carolina: 9 of 100 counties rated high (9%) · $191M expected loss a yearNorth Dakota: 5 of 53 counties rated high (9%) · $189M expected loss a yearOhio: 7 of 88 counties rated high (8%) · $226M expected loss a yearOklahoma: 11 of 77 counties rated high (14%) · $221M expected loss a yearOregon: 4 of 34 counties rated high (12%) · $57M expected loss a yearPennsylvania: 11 of 67 counties rated high (16%) · $256M expected loss a yearRhode Island: 1 of 5 counties rated high (20%) · $8M expected loss a yearSouth Carolina: 7 of 46 counties rated high (15%) · $152M expected loss a yearSouth Dakota: 5 of 66 counties rated high (8%) · $188M expected loss a yearTennessee: 10 of 95 counties rated high (11%) · $355M expected loss a yearTexas: 43 of 254 counties rated high (17%) · $1.1B expected loss a yearUtah: 0 of 27 counties rated high (0%) · $8M expected loss a yearVermont: 0 of 14 counties rated high (0%) · $18M expected loss a yearVirginia: 2 of 133 counties rated high (2%) · $76M expected loss a yearWashington: 5 of 37 counties rated high (14%) · $117M expected loss a yearWest Virginia: 2 of 55 counties rated high (4%) · $35M expected loss a yearWisconsin: 33 of 72 counties rated high (46%) · $806M expected loss a yearWyoming: 1 of 23 counties rated high (4%) · $56M 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

18 federal declarations since 1971

Declarations FEMA filed as “Freezing”, by year (2026 to date)

0241971: 1 declaration1974: 1 declaration1977: 3 declarations1984: 2 declarations1985: 1 declaration1989: 1 declaration1990: 2 declarations1991: 1 declaration1994: 1 declaration1999: 1 declaration2001: 1 declaration2003: 1 declaration2007: 1 declaration2013: 1 declaration1977: 319801990200020102020
OpenFEMA Disaster Declarations Summaries, as of 2026-09-27. Counts distinct disasters; major, emergency and fire-management declarations.

In your plan

What a Extreme Temperatures 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 Temperatures.

  1. Location

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

    National data

    FEMA's National Risk Index rates Extreme Temperatures 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 Temperatures (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)

    National data

    Every FEMA declaration filed as Freezing that included your county, back to 1953, alongside the events your own records and after-action reports describe.

  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 Temperatures 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 Temperatures

  1. 1

    We pull your county's record

    FEMA's National Risk Index rating and expected loss, your disaster declarations and NOAA's daily temperature record, gathered 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 Temperatures and where the profile falls short.

  3. 3

    You leave with a cited brief

    Likelihood, impact and readiness for Extreme Temperatures on your own scale, with each figure tied to its source. It is ready for your planning team or council.

Also in Weather Hazards

Preparing for Extreme Temperatures

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

Most plans assume severe weather is covered. We check whether yours explains why, using your county's record instead of a regional average. We reply within one business day.

Book a walkthrough

Takes about two minutes. A person reads each request.

Or start by marking your area on the map