Wisconsin heat

Every recorded heat record since 1996 · 72 counties with a record

NOAA's Storm Events Database records 1,241 heat records in Wisconsin from 1996 through June 30, 2026, about 51 a year since 2000. The deadliest was the July 2, 2012 excessive heat: 9 deaths across 5 records. Wisconsin ranks 18th of 51 states and territories by count and 23rd of 50 per square mile.

Heat in Wisconsin, 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: 1,2411996 to June 30, 2026
A year since 2000: 51average
Deaths: 59374 injuries
Damage, 2025 dollars: $100Kas filed
Busiest year: 1999180 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 Wisconsin?

Wisconsin averages about 51 heat records a year since 2000, 18th of 51 states and territories by count. The busiest year on record was 1999 (180). Per 10,000 square miles of land, Wisconsin records 229 heat records since 1996, 23rd of 50 states and territories by that measure.

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 Wisconsin have the most heat records?

Per square mile, Milwaukee County leads Wisconsin: 56 days with a heat record since 1996, 231.9 per 1,000 square miles of land. By raw count, Milwaukee County has the most heat records (57 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).

Milwaukee County 231.9 (57)
Kenosha County 176.6 (48)
Ozaukee County 150.2 (35)
Racine County 138.3 (46)
Green Lake County 100.1 (36)
Washington County 88.2 (39)
Walworth County 81.0 (45)
Green County 78.8 (46)
Marquette County 76.8 (36)
Waukesha County 76.4 (42)
Jefferson County 75.5 (42)
Rock County 72.4 (52)

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 Wisconsin?

71% of its heat records since 1996 fell in June and July. The busiest month is July (615 records).

The values, month by month

Jan 5 · Feb 24 · Mar 12 · Apr 20 · May 3 · Jun 269 · Jul 615 · Aug 191 · Sep 5 · Oct 6 · Nov 67 · Dec 24 (records).

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

What were the deadliest heat records in Wisconsin?

Wisconsin: the storms with the most deaths since 1996
Date	Record	Killed	Injured	Damage
2012-07-02	Excessive HeatRock County · forecast zone Rock One storm episode: 5 records in 5 places, 2012-07-02 to 2012-07-03; the totals are the episode's. A hot air mass settled over southern Wisconsin to start the month of July, bringing 100-degree heat to many locations for multiple days between July 2nd and July 6th. While humidity levels were relatively low considering the temperatures, maximum heat indices still climbed to between 100 and 115 during the hot spell. ...	9	0	–
1999-07-29	HeatMilwaukee County · forecast zone Milwaukee One storm episode: 5 records in 5 places; the totals are the episode's. The most intense heat wave since the killer heat wave of July 13-14, 1995, struck southcentral and southeast Wisconsin at the end of July, 1999. This most recent heat wave was responsible for directly killing 8 people (heat was the major cause of death), and indirectly killing (heat was a contributing factor) an ...	8	0	–
2012-07-02	HeatLa Crosse County · forecast zone La Crosse One storm episode: 4 records in 4 places; the totals are the episode's. Five people died from the effects of a long duration heatwave that gripped western Wisconsin from July 2nd through July 7th. Two of the deaths occurred in La Crosse County with one each in Juneau, Richland and Vernon Counties. Numerous people were also treated for heat related illnesses. The highest apparent ...	5	50	–
2001-08-06	HeatMilwaukee County · forecast zone Milwaukee One storm episode: 2 records in 2 places; the totals are the episode's. This excessive heat episode was the third, and longest, of the 2001 summer in south-central and southeast Wisconsin. Daytime heat indices reached 105 to 110, and stayed above 80 at night. Maximum air temperatures were in the lower to mid 90s, while dewpoints were in the mid 70s. Milwaukee Mitchell Field (Milwaukee ...	4	0	–
2011-07-17	Excessive HeatSauk County · forecast zone Sauk One storm episode: 5 records in 5 places; the totals are the episode's. A dome of hot and humid air over the southern and central Plains built northward into the Upper Midwest from July 17th through July 21st. High temperatures climbed into the lower to middle 90s, which combined with muggy dew points in the middle 70s to lower 80s produce heat index values between 100 and 110 for four ...	3	40	–
2012-06-18	HeatMilwaukee County · forecast zone Milwaukee One storm episode: 2 records in 2 places; the totals are the episode's. Gusty southwest winds of 20 to 35 mph brought a hot air-mass into southern Wisconsin, with maximum air temperatures reaching the lower to middle 90s, and daytime maximum heat index values of 95 or 96, beginning the afternoon of June 16th and lasting through the afternoon hours of June 20th. Overnight minimum heat ...	3	0	–
1999-07-23	HeatCalumet County · forecast zone Calumet One storm episode: 3 records in 3 places; the totals are the episode's. Over one week of hot and very humid conditions across northeast Wisconsin resulted in numerous heat related illnesses and 3 deaths due to excessive heat. A 72 year old male died in his home in Stockbridge (Calumet county), a 61 year old male died in his home in Manitowoc (Manitowoc county), and a 48 year old died in a ...	3	0	–
2011-07-17	Excessive HeatCrawford County · forecast zone Crawford One storm episode: 3 records in 3 places; the totals are the episode's. Warm and humid air invaded western Wisconsin on July 17th and remained in place for the next three days. Two people perished as a result of the excessive heat and at least eight other were treated for heat related illnesses. During this stretch, afternoon heat indices routinely topped out between 110 and 120. Little ...	2	8	$31K
2012-07-01	Excessive HeatBarron County · forecast zone Barron The Barron County Medical Examiner found that a 71 year old woman died from heat in her apartment. The wall thermometer read 105 degrees. The family stated that she refused to have an air conditioner, stating she did not like the cold. In addition, the Barron County Medical Examiner determined that a 76 year old woman ...	2	0	–
2022-06-14	Excessive HeatMilwaukee County · forecast zone Milwaukee Heat Index values ranging from 105 to 113 degrees on June 14th and rising into the lower 100's once again on June 15th. Milwaukee County Medical Examiner determined that a 39 year old female and a 89 year old male died from heat related causes. The female was found in her house and the gentleman was found collapsed in ...	2	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 Wisconsin

Wisconsin: the most damaging storms since 1993, 2025 dollars
Date	Record	Character	Killed	Injured	Damage
2011-07-17	Excessive HeatCrawford County · forecast zone Crawford One storm episode: 3 records in 3 places; the totals are the episode's.		2	8	$31K

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 Wisconsin?

Wisconsin'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: Wisconsin and the United States by decade (2020s to June 30, 2026)
Decade	Wisconsin	United States	Wisconsin's share
1996-99	260	4,355	6.0%
2000s	314	9,163	3.4%
2010s	425	16,445	2.6%
2020-26	242	26,796	0.9%

Source: NOAA NCEI Storm Events Database.

The most recent heat records in Wisconsin

The 12 most recent records, to June 30, 2026
Date	Record	Damage
2026-06-30	Excessive HeatWaukesha County · forecast zone Waukesha	–
2026-06-30	Excessive HeatWashington County · forecast zone Washington	–
2026-06-30	Excessive HeatWalworth County · forecast zone Walworth	–
2026-06-30	Excessive HeatSheboygan County · forecast zone Sheboygan	–
2026-06-30	Excessive HeatSauk County · forecast zone Sauk	–
2026-06-30	Excessive HeatRock County · forecast zone Rock	–
2026-06-30	Excessive HeatRacine County · forecast zone Racine	–
2026-06-30	Excessive HeatOzaukee County · forecast zone Ozaukee	–
2026-06-30	Excessive HeatMilwaukee County · forecast zone Milwaukee	–
2026-06-30	Excessive HeatMarquette County · forecast zone Marquette	–
2026-06-30	Excessive HeatLafayette County · forecast zone Lafayette	–
2026-06-30	Excessive HeatKenosha County · forecast zone Kenosha	–

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.