textproduct: Duluth

KEY MESSAGES

- Hot conditions are expected today and Sunday, with Heat Advisories and Extreme Heat Warnings in effect.

- Conditional threats for severe thunderstorms from late tonight through Monday morning. If thunderstorms develop, isolated to scattered severe storms are likely, capable of producing damaging winds, large hail, and frequent lightning.

- Near to slightly above average temperatures continue through the coming week, with occasional precipitation chances.

DISCUSSION

Issued at 214 PM CDT Sat Jul 25 2026

Clouds are clearing this afternoon under west to northwesterly flow, with a hot and humid day developing. Temperatures should jump up quickly with sunnier skies, pushing high temperatures into the 80s to near 90F with moist dewpoints. A Heat Advisory remains in effect for portions of the area through this evening.

As an upper level high pushes east overnight, a weak upper level disturbance along its periphery along with a marginal LLJ could force a couple storms out of a well-capped and somewhat dry air mass along the International Border and into the MN Arrowhead. The primary issue here is the actual development of storms, if that can occur, decent MUCAPE and ample bulk shear should allow for storms to grow into a respectable elevated storm severe threat, with damaging winds and large hail as the primary hazards. As the LLJ weans into Sunday morning, any areas of precipitation that do develop should weaken or diminish.

Sunday, a hot and moist airmass should push from the Dakotas into the Northland. Widespread high temperatures in the 90s (near 100F in the Brainerd Lakes region) combined with dew points in the upper 60s to mid 70s will make for an uncomfortable, and at times somewhat oppressive, heat. Heat Advisories and Extreme Heat Warnings are in effect. With that heat and humidity, an impressive reservoir of instability is expected to develop, with models suggesting 3000- 4000+ J/kg of MUCAPE across Minnesota, Wisconsin, and the UP. Along with that, around 50 knots of bulk shear could combine with steep mid level lapse rates to develop clusters of storms from the International Border and southeastward across the aforementioned region. With the heat we're expecting, there will be a cap to overcome, which seems most likely to occur in the late afternoon to evening hours, but the potential for the cap to not break is there, limiting our PoP forecast for now. Storms will likely be pretty quick if they develop, cruising from northwest to southeast with a damaging wind and large hail threat. Our entire area is in a Slight Risk (level 2/5) for Sunday. As additional upper level shortwaves continue to move along the edge of the high pressure, some storms could continue to form and propagate over the MN Arrowhead into NW WI Monday morning, where a Day 3 Marginal risk is in effect.

Monday and through the work week, temperatures temper slightly, but are still largely expected to be around to above normal with afternoon highs in the upper 70s to upper 80s and overnight lows in the 50s and 60s. We remain in a somewhat stagnant pattern stuck between an upper level high over the Southwest to Central Plains and semi-transient upper level lows moving over central to eastern Canada. This should continue to put us in position to see the influence of occasional ridge running disturbances which could bring spotty rain showers and thunderstorms. Some global models are suggesting the potential for a slightly stronger upper level shortwave to bring a more potent system to the area late in the week, but confidence is extremely low in any solutions that far out at this point.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1252 PM CDT Sat Jul 25 2026

A MVFR cloud deck should continue to erode from northwest to southeast today, bringing widespread VFR conditions to all terminals. Light winds are expected through the TAF period. Some MVFR fog is possible at HIB and HYR overnight into Sunday morning. There is a very low (10-15% chance) for some showers and thunderstorms at INL overnight.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 214 PM CDT Sat Jul 25 2026

|Southwesterly winds continue to die down through this afternoon and evening. An area of shallow dense marine fog along the North Shore should persist into this evening, and then slowly become less widespread overnight. Sunday, winds switch around and come onshore, with some afternoon gusts up to 15 knots possible for the head of the lake and South Shore. Monday, breezy northeast winds pick up, with some afternoon gusts of 15-20 knots for the head of the lake and Outer Apostle Islands. This time period will need to be monitored for possible Small Craft Advisories. With continued high dewpoints, areas of dense fog could be possible on the lake. However, with northeast winds expected to reduce the upwelling cold water along the North Shore, the coverage and magnitude is uncertain. There is a slight chance for thunderstorms, some possibly severe, very late tonight through Monday morning, with the best chance Sunday afternoon and evening. Strong winds, large hail, and frequent lightning could be possible with any storms that develop.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

FIRE WEATHER

Issued at 214 PM CDT Sat Jul 25 2026

Looking ahead, the pattern for fire weather concerns is fairly rinse and repeat each day. We have slightly above normal temperatures, leading to afternoon relative humidity dropping into the 40-50% range most days. There are currently no signals for periods of significant winds, but afternoon gusts 10-15mph are possible through much of the week. From late tonight through Monday morning, some areas of showers and thunderstorms are possible, but not guaranteed. If thunderstorms do form, isolated to scattered severe storms are possible, capable of producing large hail, damaging winds, and frequent lightning. Precipitation amounts will be spotty, dependent on where the thunderstorms end up, but those areas that do get showers/storms could see 0.25-1" of quick rainfall. Monday and through the week, we remain in a pattern that could bring more spotty chances of showers and thunderstorms on and off but confidence is low in timing and placement.

See the Fire Weather Forecast product for a more thorough breakdown of fire weather conditions.

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory from 11 AM to 9 PM CDT Sunday for MNZ010>012- 019>021. Heat Advisory until 9 PM CDT this evening for MNZ010-018-019- 025-026-033>038. Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for MNZ018- 025-026-033>038. WI...Heat Advisory from 11 AM to 9 PM CDT Sunday for WIZ004-009. Heat Advisory until 9 PM CDT this evening for WIZ001>003- 006>008. Extreme Heat Warning from 11 AM to 9 PM CDT Sunday for WIZ001>003-006>008. MARINE...Dense Fog Advisory until 9 PM CDT this evening for LSZ140>143. Heat Advisory from 11 AM to 9 PM CDT Sunday for LSZ142.