textproduct: Duluth

KEY MESSAGES

- The warming trend continues with Tuesday expected to be the hottest day of the work week. Highs will be in the 80s with a few values near 90.

- There is a Marginal Risk (threat level 1 out of 5) for severe storms this afternoon and evening over a portion of the Minnesota Arrowhead. Hail up to half-dollar size (1.25 inch) and wind gusts to 65 mph are the main threats from severe storms.

- Off and on chances for showers and storms persist through Wednesday.

DISCUSSION

Issued at 356 PM CDT Mon May 25 2026

Today and tonight... Satellite imagery is beginning to show cumulus development in the Arrowhead, within an area of instability that is beginning to overcome the CIN that is in place, mainly in the Arrowhead. Bulk shear is marginal at best right now, but stronger winds moving in aloft over the next few hours should cause the shear to increase as well. A cold front moving in from the northwest which is about to enter the northwest corner of the CWA should help initiate convection, as it has already done in Ontario. The front will also bring stronger surface winds and will come along with the stronger upper level winds to increase shear. A few of the storms triggered by this front could become severe, with large hail and damaging winds. The storms will track in an easterly direction, gradually weakening as they move across Lake Superior and northwest Wisconsin before dissipating. Meanwhile, deep atmospheric mixing will drive relative humidity values down around 25 percent in the Brainerd Lakes region north to Koochiching count, creating near-critical fire weather conditions through the early evening. The dry RH value extend east along the Borderlands, but with weaker winds there, concerns are lower. Heat has been running warmer than forecast along our northern border, but with convection initiating and creating cloud cover, that should cool back off soon. Behind the cold front, winds turn northwest and temperatures cool off for overnight.

Tuesday...Today's cold front will sag south and stall, draping west to east across the southern half of the area. We are expecting the hottest temperatures of the week along and south of that front, with forecast highs in the upper 80s and lower 90s for most inland locations. A Heat Advisory may be needed for parts of the area. As is typical, onshore flow along the North Shore will keep temperatures in the 70s there. North of the front, very dry air will also build into the Borderlands, where afternoon relative humidity values will drop between 20 and 30 percent, resulting in near-critical fire weather concerns. Strong daytime heating will build moderate instability along and south of the front, and the front itself will serve as a trigger for another round of afternoon and evening thunderstorms. These storms will have only weak shear and moderate instability, so we may be looking at a few marginally severe storms, mainly for parts of northwest Wisconsin south of the front.

Wednesday...the surface boundary sags still farther south as Canadian high pressure pushes south toward the Great Lakes. Winds for all of the area will turn east to northeast, and with a slightly tighter pressure gradient, surface winds will increase over western Lake Superior, with gusts up to 25 mph. This will cause temperatures to cool significantly, with 60s and lower 70s near the lake, while farthern inland areas remain hot in the 80s, though not as warm as Tuesday. Isolated showers and thunderstorms remain possible on Wednesday afternoon in the general vicinity of the boundary to our south.

Late this week through next weekend...The surface high pressure builds down over the forecast area beginning Thursday along with ridging aloft should keep the weather dry and mostly sunny. This pattern continues through Friday and next weekend. Generally east to southeast winds will maintain the cool lake breeze advantage, keeping lake-adjacent highs in the 60s and 70s while inland locations climb back into the mid 70s to mid 80s which is near to above normal values. This is just the general trend though, and there are indications we may get some diurnally driven or weak shortwaves to kick off some chances for showers and storms, perhaps Friday or Saturday. The ensembles have us dry for now, but would not be surprised to add some pops back in at some point.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 126 PM CDT Mon May 25 2026

VFR conditions will prevail across the terminals through most of the period. A cold front arriving from the northwest late this afternoon and evening will trigger scattered showers and thunderstorms, with brief MVFR restrictions possible under heavier cores. Have included PROB30 groups for the sites and times when they are most likely. Winds will remain southwesterly around 10 knots with gusts up to 20 knots through sunset before veering to the northwest behind the cold front and diminishing overnight. Winds remain 8kts or less through the end of the forecast. Patchy fog may develop between 08Z and 12Z Tuesday morning, causing MVFR, perhaps IFR visibility reductions at DLH, HIB, and BRD before clearing to VFR.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 356 PM CDT Mon May 25 2026

East to northeast winds today generally in the 5 to 15 knot range will gradually veer southwest tonight. There is a chance of thunderstorms that will roll across the lake sometime this evening. A few storms may become severe northeast of Tofte, capable of 50 knot winds and half-dollar size hail. Winds veer southwest and west tonight, then back around to northeasterly at 5 to 10 knots on Tuesday with waves under one foot. Wednesday and Wednesday night, strengthening northeast winds and building waves will likely create hazardous conditions, and Small Craft Advisories may be needed. Winds and waves diminish going into Thursday, even as winds remain northeast.

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

FIRE WEATHER

Issued at 126 PM CDT Mon May 25 2026

Near-critical fire weather conditions to affect the Brainerd Lakes region north through Koochiching county this afternoon, driven by minimum relative humidity values dropping into the 25 to 30 percent range and southwest wind gusts reaching 15 to 20 mph. On Tuesday, the dry, near- critical relative humidity values between 20 and 30 percent will shift into the Borderlands region, accompanied by east winds of 5 to 10 mph. Winds turn east to northeast on Wednesday as a prominent inland lake breeze develops, keeping the lakeside cooler while dry relative humidity values of 25 to 35 percent remain possible further inland.

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

CLIMATE

Issued at 126 PM CDT Mon May 25 2026

Hot, summer-like temperatures today and Tuesday could produce high temperatures nearing daily record highs at several climate sites. Below are the sites where forecast high temperatures are within 3 degrees of their record values. Have added KDLH for reference.

Record High Temperatures:

Monday, May 25: Forecast Record KINL: 86 ........ 88 in 1919 KBRD: 88 ........ 90 in 2018 KHIB: 84 ........ 87 in 2010 KDLH: 81 ........ 89 in 2018

Tuesday, May 26: Forecast Record KINL: 82 ........ 88 in 1919 KBRD: 90 ........ 92 in 2018 KHIB: 86 ........ 88 in 1978 KDLH: 80 ........ 92 in 2018

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...None.