On June 29th, a favorable synoptic weather pattern brought extreme heat to southeast Minnesota as ample moisture resulted in remarkably high dewpoints. Consequently, heat indices soared well above 100 degrees with numerous locations seeing heat indices of 105 to 115 degrees.
Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ARX wrote it up.
On June 29th, a favorable synoptic weather pattern brought extreme heat to southeast Minnesota as ample moisture resulted in remarkably high dewpoints. Consequently, heat indices soared well above 100 degrees with numerous locations seeing heat indices of 105 to 115 degrees.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS La Crosse, WI wrote its last area forecast discussion before the first event at Jun 29, 12:40 PM CST, 20 minutes earlier. Its key messages:
Area Forecast Discussion
National Weather Service La Crosse WI
140 PM CDT Mon Jun 29 2026
.KEY MESSAGES...
- Dangerous heat persists through at least Wednesday, but
oppressive temperatures/humidity linger through late week. An
Excessive Heat Warning remains in effect for most of the
region while a Heat Advisory remains in effect for Taylor
County in Wisconsin.
- Periodic storms are possible this week (20-40%), but
timing/location remains uncertain. Storms that develop could
become strong to severe.
&&
.DISCUSSION...
Issued at 139 PM CDT Mon Jun 29 2026
This Afternoon - Tuesday: Dangerous Heat and Storm Potential
Dangerous heat is expected areawide over the next 24-36 hours.
A very moist airmass remains in place this afternoon with
dewpoints in the mid to upper 70s across much of the area which
is expected to remain in place throughout the day Tuesday. Overall
expectations are for temperatures to climb into the low to mid
90s given 850hPa temperatures of 20-22C, resulting in heat
indices around 75F tonight and in the upper 90s to mid 100s
during the day Tuesday.
There is some concern for strong/severe storms tonight, mainly
northwest of a line from Charles City, IA to Wausau, WI
(10-30%) though expectations are for most of (if not all of)
these storms to miss our area due to strong capping in place
given 700hPa temperatures of 12+C. However, there are some CAM
solutions suggesting a line of convection moves west-east
through the region after midnight on the nose of an
strengthening nocturnal low level jet and 850hPa moisture
transport. Confidence is low in which scenario will win out, but
currently leaning towards most storm activity remaining out of
our area as this has the greatest consensus amongst model
guidance. Regardless, if storms do affect the area tonight, the
primary hazard will be damaging winds.
Additional concern for strong/severe storms comes Tuesday
afternoon, mainly north of I-94 (20-30%). The expected heat and
humidity Tuesday will continue to support the volatile
atmosphere in place with MUCAPE values exceeding 3000 J/kg in
most model solutions along with effective bulk shear of
30-35kts. Within this environment, a surface boundary associated
with the surface low over southern Canada lays out and stalls
from northeast to southwest from northern Wisconsin to northern
Iowa with the favorable atmosphere in place ahead of it. Above
the surface features, a ribbon of 700hPa positive vorticity and
divergence associated with the right entrance region of a nearby
jet core could support storm development, although the overall
QG forcing is fairly weak and nebulous.
The biggest question is if convective initiation can even occur
in this environment. 700hPa temperatures remaining around 12C
may make it challenging for convection to develop, especially
given the nebulous forcing. Many CAM solutions do suggest the
bulk of development remains across northern Wisconsin. There is
also the issue of how the storms overnight evolve and their
influence on where mesoscale boundaries set-up which would also
influence convective initiation. All of this said, if
convection is able to develop, expectations are for damaging
winds to be the primary threat. The aforementioned warm
temperatures aloft make large hail unfavorable as WBZ heights
are forecast to be above 10kft, but certainly can't rule out
some smaller stones up to 1 inch given the ample instability.
Wednesday - Friday: Hot/Humid Conditions Continue and Storm Chances
Wednesday morning brings additional strong/severe storm
potential (50-70%) along the aforementioned stationary boundary
as it lays out west-east across the region. A subtle shortwave
lifts northward atop this feature with ample moisture remaining
in place. MUCAPE of 2500+ J/kg will exist along the boundary
with 30-35kts of effective bulk shear. Damaging winds and hail
up to 1 inch again seem possible with storms that develop during
this period.
Slightly cooler temperatures are depicted in ensemble suites
Wednesday through Friday as the upper ridge begins to shift ever
slowly eastward although temperatures still remain in the upper
80s to low 90s. The evolution of any possible convection may
also act to further temper afternoon highs. However, dewpoints
remain in the low to mid 70s and with little temperature relief
overnight, confidence is high in heat impacts lingering through
at least Wednesday.
Holiday Weekend - Early Next Week: Seasonable, Additional Showers
and Storms
As we head into the holiday weekend, the upper level pattern
becomes more zonal as compared to today/Tuesday allowing various
shortwaves to traverse the mean 500hPa flow. These shortwaves
will tend to knock down temperatures aloft as well as at the
surface with an overall cooling trend noted in the 29.00z LREF.
Surface highs fall into the low to mid 80s, near normal for this
time of year, although there is a fair degree of uncertainty in
exact temperature values as the 25th-75th percentile spread is
around 5-10 degrees with some outliers still suggesting the 90s
could be in play. Additional shower and storm chances also exist
over the holiday weekend with the 29.13z NBM currently
suggesting 30-60% probabilities for measurable rainfall, but
there is still plenty of variation to work out over the coming
days.
&&
.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1231 PM CDT Mon Jun 29 2026
Gusty southerly winds will persist through the TAF period with
VFR conditions expected. As a low pressure system slides across
the Upper Midwest, there is a low chance (20%) for passing
showers after midnight tonight.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Extreme Heat Warning until 9 PM CDT Tuesday for WIZ029-032>034-
041>044-053>055-061.
Heat Advisory until 9 PM CDT Tuesday for WIZ017.
MN...Extreme Heat Warning until 9 PM CDT Tuesday for MNZ079-086>088-
094>096.
IA...Extreme Heat Warning until 9 PM CDT Tuesday for IAZ008>011-018-
019-029-030.
&&
DISCUSSION...Falkinham
AVIATION...JAWHazardous Weather Outlook National Weather Service La Crosse WI 135 AM CDT Mon Jun 29 2026 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ029-032>034- 041>044-053>055-061-301100- Mitchell-Howard-Winneshiek-Allamakee-Floyd-Chickasaw-Fayette- Clayton-Wabasha-Dodge-Olmsted-Winona-Mower-Fillmore-Houston-Clark- Buffalo-Trempealeau-Jackson-La Crosse-Monroe-Juneau-Adams-Vernon- Crawford-Richland-Grant- 135 AM CDT Mon Jun 29 2026 This Hazardous Weather Outlook is for portions of north central Iowa...northeast Iowa...southeast Minnesota...central Wisconsin... southwest Wisconsin and west central Wisconsin. .DAY ONE...Today and Tonight An Extreme Heat Warning remains in effect from 8 am today to 9 pm Tuesday. Dangerously hot conditions with heat index values of 100 to 110 are expected. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Daytime heat index values will reach above 100 degrees through at least mid-week. Multiple rounds of storms could impact the region this week, some of which could be severe. However, confidence in the location and severity of these storms is low at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed tonight in southeast Minnesota and northeast Iowa. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. WIZ017-301100- Taylor- 135 AM CDT Mon Jun 29 2026 This Hazardous Weather Outlook is for portions of north central Wisconsin. .DAY ONE...Today and Tonight A Heat Advisory remains in effect from 8 am today to 9 pm Tuesday. Heat index values of 95 to 105 are expected. Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Daytime heat index values will reach above 95 degrees through at least mid-week. Multiple rounds of storms could impact the region this week, some of which could be severe. However, confidence in the location and severity of these storms is low at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation may be needed tonight in north-central Wisconsin. .EMERGENCY MANAGEMENT COORDINATION... No webinar is scheduled. Boyne
The national radar mosaic for the moment the first event began.
7 excessive heat. Local standard time, as filed.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 102 to 107 degrees across Dodge County. The highest heat index of 107 degrees was reported in Hayfield.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 103 to 109 degrees across Fillmore County. The highest heat index of 109 degrees was reported in Preston.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 105 to 114 degrees across Houston County. The highest heat index in the county of 114 degrees was reported in Hokah.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 104 to 114 degrees across Mower County. The highest heat index in the county of 114 degrees was reported in Lyle.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 101 to 104 degrees across Olmsted County. The highest heat index in the county of 104 degrees was reported in Stewartville.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 106 to 116 degrees across Wabasha County. The highest heat index in the county of 116 degrees was reported in Lake City.
Extreme heat moved into the region for the afternoon and early evening hours on June 29th bringing heat indices of 105 to 112 degrees across Winona County. The highest heat index in the county of 112 degrees was reported in La Crescent.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2026Every state in 2026This day in weather historyWarnings in Minnesota, June 2026
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1355137, 1355138, 1355139, 1355141, 1355142, 1355143, 1355144.