PlainHazard

Iowa heat

Every recorded heat record since 1996 · 99 counties with a record

NOAA's Storm Events Database records 888 heat records in Iowa from 1996 through June 30, 2026, about 48 a year since 2000. The deadliest was the June 30, 2019 heat in Woodbury County: 1 death. Iowa ranks 22nd of 51 states and territories by count and 28th of 50 per square mile.

Heat in Iowa, 1996 to 2026

Heat records per year (NOAA Storm Events); 2026 to June 30, 2026.

  • recorded, no damage figure
  • under $1 million
  • $1 million or more
  • $10 million or more
  • $100 million or more, or 10 deaths
  • $1 billion or more, or 100 deaths
  • a year's colour: its recorded damage or deaths
  • a year with a death
Records
8881996 to June 30, 2026
A year since 2000
48average
Deaths
450 injuries
Damage, 2025 dollars
$9.4Mas filed
Busiest year
2011105 records

Source: NOAA NCEI Storm Events Database, records through June 30, 2026; deaths and damage as filed, damage in 2025 dollars. Search the record at NCEI.

Are heat records common in Iowa?

Iowa averages about 48 heat records a year since 2000, 22nd of 51 states and territories by count. The busiest year on record was 2011 (105). Per 10,000 square miles of land, Iowa records 159 heat records since 1996, 28th of 50 states and territories by that measure.

  1. 1. New Jersey 2320
  2. 2. Delaware 1555
  3. 3. Maryland 1330
  4. 4. Oklahoma 685
  5. 5. Illinois 590
  6. 6. Mississippi 584
  7. 7. Louisiana 576
  8. 8. Missouri 547
  9. 9. Tennessee 540
  10. 10. Puerto Rico 537
  11. 28. Iowa 159

Source: NOAA NCEI Storm Events Database, records since 1996, per 10,000 square miles of land area (Census Bureau 2024 Gazetteer; places under 1,000 square miles not ranked). Damage colours: Storm Events damage, 2025 dollars.

Which counties in Iowa have the most heat records?

Per square mile, Montgomery County leads Iowa: 30 days with a heat record since 1996, 70.7 per 1,000 square miles of land. By raw count, Montgomery County has the most heat records (31 since 1996); large counties collect more records simply by covering more ground, so the ranking counts days with a record per unit of area (a storm filed for several forecast zones adds several records but one day).

  1. Montgomery County 70.7 (31)
  2. Dickinson County 63.1 (24)
  3. Osceola County 62.7 (25)
  4. Ida County 60.3 (26)
  5. Mills County 59.4 (26)
  6. Fremont County 58.7 (30)
  7. Page County 54.2 (30)
  8. Lyon County 45.9 (27)
  9. O'Brien County 43.6 (25)
  10. Buena Vista County 43.5 (25)
  11. Cherokee County 43.3 (25)
  12. Clay County 42.3 (24)

Source: NOAA NCEI Storm Events Database, days with a record in the county since 1996 per 1,000 square miles of land (Census Bureau 2024 Gazetteer); in brackets, the count of records.

When is the heat season in Iowa?

85% of its heat records since 1996 fell in July and August. The busiest month is July (524 records).

The values, month by month

Jan 1 · Feb 0 · Mar 0 · Apr 0 · May 0 · Jun 128 · Jul 524 · Aug 231 · Sep 4 · Oct 0 · Nov 0 · Dec 0 (records).

Source: NOAA NCEI Storm Events Database, records by the month they began, since 1996.

What were the deadliest heat records in Iowa?

Iowa: the storms with the most deaths since 1996
DateRecordCharacterKilledInjuredDamage
2019-06-30 HeatWoodbury County · forecast zone Woodbury With temperatures peaking in the mid to upper 90's and dew points in the lower to mid 70's, heat index values ranged from 100 to 108 during the afternoon and early evening hours. A 16-month old female died around 1500CST after being left alone in a vehicle in Sioux City for an extended period of time. 1 0 –
2006-07-17 HeatPolk County · forecast zone Polk A very unstable airmass was in place over Iowa during the afternoon of the 17th, though it was also quite capped. The 700 mb temperature was in the 14 to 15 C. range, making it difficult for thunderstorm activity to initiate. Plenty of moisture was available with CAPE values in the 6000 to 8000 J/kg range based on the ... 1 0 –
2001-08-05 HeatPolk County · forecast zone Polk Very warm and humid conditions that began in the last part of July continued into August. Temperatures during the day warmed into the 90s, with overnight lows remaining in the 70s. Dew point temperatures held in the mid 70s to low 80s through most of the time. An elderly woman passed away in Des Moines on the 5th. She ... 1 0 –
2016-06-11 HeatPolk County · forecast zone Polk A 6 month old boy was left in an attended vehicle outside a business while the father was inside the business. The high at KDSM was 91 degrees that afternoon with the highest heat index of 97. 1 0 –

Source: NOAA NCEI Storm Events Database: deaths direct and indirect, as filed by the National Weather Service, summed over each storm (one episode, or one named storm filed by several offices). Storm names from the titles of FEMA declarations that name the storm's counties.

The costliest heat records in Iowa

Iowa: the most damaging storms since 1993, 2025 dollars
DateRecordCharacterKilledInjuredDamage
2011-07-17 Excessive HeatAllamakee County · forecast zone Allamakee 0 4 $29K

Source: NOAA NCEI Storm Events Database: property and crop damage as estimated by the National Weather Service, in 2025 dollars.

Are heat records becoming more frequent in Iowa?

Iowa's count per decade against the whole country's, and its share. NOAA recorded every event type only from 1996, so earlier decades are not comparable; the share of the national total is the fairer comparison across decades.

Heat: Iowa and the United States by decade (2020s to June 30, 2026)
DecadeIowaUnited StatesIowa's share
1996-99874,3552.0%
2000s1079,1631.2%
2010s44416,4452.7%
2020-2625026,7960.9%

Source: NOAA NCEI Storm Events Database.

The most recent heat records in Iowa

The 12 most recent records, to June 30, 2026
DateRecordCharacterKilledInjuredDamage
2026-06-29 HeatMonona County · forecast zone Monona 0 0 –
2026-06-29 Excessive HeatWinneshiek County · forecast zone Winneshiek 0 0 –
2026-06-29 Excessive HeatMitchell County · forecast zone Mitchell 0 0 –
2026-06-29 Excessive HeatHoward County · forecast zone Howard 0 0 –
2026-06-29 Excessive HeatFloyd County · forecast zone Floyd 0 0 –
2026-06-29 Excessive HeatFayette County · forecast zone Fayette 0 0 –
2026-06-29 Excessive HeatClayton County · forecast zone Clayton 0 0 –
2026-06-29 Excessive HeatChickasaw County · forecast zone Chickasaw 0 0 –
2026-06-29 Excessive HeatAllamakee County · forecast zone Allamakee 0 0 –
2026-06-29 Excessive HeatIda County · forecast zone Ida 0 0 –
2026-06-29 Excessive HeatWoodbury County · forecast zone Woodbury 0 0 –
2026-06-29 Excessive HeatPlymouth County · forecast zone Plymouth 0 0 –

Source: NOAA NCEI Storm Events Database, records through June 30, 2026; the newest months are revised by NCEI as reports arrive. Search the record at NCEI.

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