textproduct: Duluth

KEY MESSAGES

- Dense fog expected for much of the Northland through early this morning.

- Scattered showers and isolated thunderstorms possible today into this evening, with the best potential in northeast Minnesota and the Arrowhead. The risk of storms shifts this evening and overnight to the Brainerd Lakes and inland northwest Wisconsin.

- Summer-like heat for Memorial Day through much of this week, with the hottest temperatures on Memorial day and Tuesday when near-record high temperatures are possible.

- Much of this week will be primarily on the drier and sunnier side for most of the Northland, though there will be isolated shower/storm chances at times on a daily basis through mid- week. Potential for near-critical fire weather conditions will need to be monitored closely each afternoon into early evening this week.

DISCUSSION

Issued at 112 AM CDT Sun May 24 2026

Current Overnight - Sunday Evening:

Calm to very light winds and mostly clearing skies tonight combined with lingering near-ground moisture is already supporting dense fog development. Expect this dense fog to expand across much of the Northland during the current overnight into this morning. A Dense Fog Advisory has been issued for most of the Northland aside from Koochiching County in north- central MN, and Ashland, Iron, and Price counties in north- central WI. Expansions to the advisory may be needed. Visibilities should improve as we progress to a few hours past sunrise this morning. Low temperatures bottom out in the low to upper 40s early this morning.

Mid- and upper-level shortwave energy could kick off some isolated showers and perhaps an isolated storm or two this morning in north-central MN that would then move east through the Arrowhead and Bayfield Peninsula into midday/early afternoon. No severe weather expected with this round.

Expect a noticeable increase in temperatures today as southwesterly winds advect warmer temperatures into the Northland. High temperatures warm into the 70s and pockets around 80F away from the immediate vicinity of Lake Superior, with slightly cooler temperatures near the Lake and for the North Shore under primarily sunny skies where slight onshore flow could provide a weak lake breeze. By mid to late afternoon, several high-resolution models suggest a few showers and storms developing on the northern extent of a 600-1100 J/kg MLCAPE gradient in northeast MN and sliding east-southeast through parts of the North Shore, Twin Ports, and NW WI South Shore counties. Combined with steep mid-level lapse rates, dry air aloft, and 25-35 kt of 0-6km bulk shear, the main hazards with these storms would be half inch to penny size hail and occasional cloud-to-ground lightning if they do form. The main limitation on organization for these storms is a lack of forcing for upward ascent and fairly weak low-level flow. As of this latest forecast update, the potential for severe storms remains less than 5 percent.

With warmer temperatures and dry low-level air for much of today, some localized pockets of near-critical fire weather conditions could develop this afternoon into early evening. The areas with the best potential of reaching minimum relative humidities of 25-30% are in the Brainerd Lakes east into the St. Croix River Valley and NW WI Pine Barrens. Most other locations in the Northland away from Lake Superior see minimum relative humidities bottom out between 30-40% this afternoon. Late morning and afternoon southwesterly winds will also gust up to 15 to locally 20 mph for much of the Northland with daytime mixing alongside the lower humidities.

Sunday Night - Monday:

For Sunday night into early Monday morning, expect a warm front moving northward to interact with the nose of a low-level jet and create scattered, elevated showers and storms for parts of north- central MN into inland NW WI. The better coverage should remain just south of the Northland in east-central MN into west- central WI. Severe weather is not expected with these storms, but MUCAPE values of 500-1000 J/kg, mid-level lapse rates around 7 C/km, and 0-6km bulk shear of 30-35 kt would allow for main storm hazards of small hail and cloud-to-ground lightning.

There is also a 10-20% chance for thunderstorms in north-central Minnesota tonight into early Monday morning. These storms are not expected to be severe.

The summer-like heat ramps up on Monday with high temperatures in the low to upper 80s for most of the Northland aside from cooler temperatures immediately near Lake Superior. This is due to an anomalously strong ridge aloft starting to move over the Central CONUS and Northern Plains. Near-record high temperatures are also possible for several climate sites on Monday (see "Climate" section below). Daytime southwest wind gusts of around 15-20 mph and minimum afternoon relative humidity values of 25-40% could once again lead to near-critical fire weather conditions on Monday. This time the lowest relative humidity values of 25-30% are favored in north-central MN where temperatures will be highest and daytime boundary layer mixing depths will be the deepest.

A surface low pressure moving through northwest Ontario Monday afternoon and evening along with some weak shortwave energy aloft is forecast to bring a 20-30% chance for scattered showers and storms through far northern Minnesota and the Arrowhead. There remains some question regarding if the very warm 850 and 925 temperatures and will be too warm and act as an effective "cap" to storm development or if surface temperatures in the 80s will be enough to reach the convective temperature. Should storms form, access to upwards of 1500-2500 J/kg of MUCAPE, dry mid-levels with mid-level lapse rates of 6-6.5 J/kg, and 0-6 km bulk shear of 35-40 kt could produce semi-organized convection and a low end threat for large hail and strong winds.

Tuesday - Rest of the Week:

The main axis of the ridge will be present in the Northland on Tuesday, leading to the hottest day of the forecast this week. Inland areas should see high temperatures soar into the upper 80s to low 90s, near record highs yet again. Winds will be on the lighter side for Tuesday, so some easterly winds near Lake Superior could push a lake breeze into the Twin Ports vicinity and North shore, keeping afternoon temperatures for those locations several degrees cooler than farther inland. With widespread "Moderate Heat Risk" criteria and Wet Bulb Globe Temperatures forecast to be in the upper 70s to around 80 degrees for many inland locations, a Heat Advisory may be needed for Tuesday. The hot temperatures combined with mainly dry conditions should also push minimum relative humidities back into the 25-35% range on Tuesday, leading to potential near- critical fire weather conditions yet again despite lighter winds.

A stationary front setting up over southern portions of the Northland could also kick off some showers and storms (10-20% chance) late Tuesday into Tuesday night with and following peak daytime heating.

Temperatures remain above normal through the mid to late week timeframe due to upper-level ridging remaining overhead, but several degrees cooler than what we will see on Monday and Tuesday. Surface high pressure centered northeast of the Northland will also favor onshore flow Wednesday through late week, aiding in lake breezes pushing farther inland. Additional isolated diurnal shower/storm potential continues on Wednesday (10-30%) in our southern areas, but most of the Northland will likely remain dry once again. Drier east winds associated with the high pressure late this week should keep precipitation chances at bay those days. The trend of low relative humidities and potential for areas of near-critical fire weather conditions persists on a daily afternoon/early evening basis through at least the end of this work week.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1220 PM CDT Sun May 24 2026

VFR conditions across the forecast area. Radar shows a few areas of showers moving across the Arrowhead that are tapering off as they run into Lake Superior. Satellite does show some developing cumulus towers across northern MN which could lead to some isolated thunderstorms this afternoon. Overnight a low level jet will try to nudge some more storm activity into the Northland once again. Confidence is not high in these storms making into the terminals at this time. Best timing has been highlighted in the prob30 groups for impacted terminals.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 112 AM CDT Sun May 24 2026

Light and variable winds expected through the current overnight hours. Lighter winds are expected today through Tuesday with a stable layer developing on Lake Superior. Winds remaining under 15 knots and waves dropping to 1 to 2 feet or less. A Marine Dense Fog Advisory has been issued for the current overnight hours into Monday morning as warm to hot temperatures moving over cold waters and a stable marine layer should be favorable for a prolonged period of Marine fog. This fog advisory may need to be extended in time, as well.

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

FIRE WEATHER

Issued at 112 AM CDT Sun May 24 2026

RH recovers to near 100% for many areas during the current overnight hours along with many areas seeing dense fog through the early morning today. After fog burns off by mid-morning, today will be the start of a substantial warming trend which may bring near-critical fire weather conditions to parts of the area through much of the upcoming work week. Minimum relative humidity will drop into the 25 to 35 percent range over much of the area today, with the best potential for 25-30% RH in the Brainerd Lakes region east into the St. Croix River Valley and the NW WI Pine Barrens. Southwest winds of 5 to 10 mph with gusts of 15-19 mph are forecast for today, strongest during the afternoon, then becoming light this evening. Minimum RH values should dip into the 30s for much of next week, with winds generally lighter than Sunday. Looking at similar conditions for Monday, though lowest RH will be over north-central MN. Similarly low RH on Tuesday, but winds will be even lighter. Low RH in the 25-35% range continues into the latter half of the week, as well, but with winds being predominately out of the east to southeast with gradually less hot conditions. Most days this week will see primarily rain-free and mostly sunny conditions, though each day from today through Wednesday will have chances (generally 10-30%) for showers and storms on a very isolated basis.

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

CLIMATE

Issued at 112 AM CDT Sun May 24 2026

Hot, summer-like temperatures on Monday and Tuesday could produce high temperatures nearing daily record highs at several climate sites. There is also potential for a near-record warm daily low temperature at Hibbing early Wednesday morning depending on how quickly temperatures cool off late Wednesday evening.

Record High Temperatures:

Monday, May 25: Record Forecast KINL: 88/1919 85 KBRD: 90/2018 88 KHIB: 87/2010 84

Tuesday, May 26: Record Forecast KINL: 88/1919 86 KBRD: 92/2018 91 KHIB: 88/1978 89 KASX: 91/2018 89

Record Warm Minimum Temperatures:

Tuesday, May 26: Record Forecast KHIB: 60/1988 57

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Dense Fog Advisory until 10 AM CDT Monday for LSZ140>142.