textproduct: Duluth

KEY MESSAGES

- Hot today with strong west winds today in the wake of a cold front this morning leading to near-critical fire weather conditions as west winds gust to 20 to 30 mph.

- There is a risk for isolated strong to severe storms to rapidly develop in northwest Wisconsin along the exiting the cold front this afternoon in the 4 PM to 7 PM timeframe. While the probability for any storms developing is very low (10 to 30 percent), if storms develop there is a high likelihood they would quickly become severe and capable of producing very large hail, damaging winds, and possible a tornado.

- Drier with more seasonable temperatures on Wednesday, gradually warming up again towards next weekend.

DISCUSSION

Issued at 117 PM CDT Mon Jul 20 2026

A pattern change with cooler and drier air across the Northland mid- week, then a return to warmer temperatures late week into next weekend. Occasional chances for precipitation, but no significant precipitation amounts nor signal for severe storms through the next 5-7 days, with long-range outlooks heavily favored toward above normal temperatures through the end of July.

Late today and tonight a secondary cold front moves north to south through the region bringing low level moisture along the front and cooler and drier air in its wake through mid-week as high pressure builds in with north-northwesterly flow aloft. The airmass aloft is so cool with 850mb temps of +2-6C it is actually below the tenth percentile of climatology for the International Falls RAOB climatology for this time of year.

There are two areas of potential strong to severe storms this afternoon, though already as of noon the window of opportunity is limited and closing fast for organized severe weather.

NW Wisconsin Severe Threat: There is sufficient instability along a cold frontal boundary tracking east into northern Wisconsin with steep mid-level lapse rates visualized on the water vapor channel satellite imagery today. The biggest challenge will be whether there can be enough forcing to kick off thunderstorms in our CWA before the front exits to the southeast, and even if storms pop up in the 3- 5 pm timeframe, the nearly 50 knot mean-level winds will quickly take organized storms out of our CWA within an hour or two. While the threat is conditional, the conditions should convection develop would support all modes of severe weather with supercellular storm modes, very large hail, damaging winds, and a tornado possible.

Otherwise in northeast Minnesota: Behind the first cold front, this environment is not as extreme as northwest Wisconsin, but with 500 j/kg and 15-20 knots of deep layer shear a few strong to near severe storms are possible. The early afternoon SPC Day 1 Convective Outlook aligns with our thinking of this being a Marginal (Level 1 out of 5) severe weather risk, with "skinny" cape profiles and dry air at mid/upper levels causing any initial updrafts to be fairly thin, though perhaps balanced with the limited deep layer shear. Small hail/gusty winds likely the biggest impacts of the strongest storms that pop up this afternoon.

Tonight the final cold front moves north to south bringing with it low level moisture/clouds and then drier air in its wake. This will lead to cloud cover overnight into Tuesday with light rain showers (or perhaps even more like drizzle/sprinkles towards Tuesday morning) but overall little in the way of measurable precipitation.

With the cooler airmass tomorrow highs will range from the mid 60s in the MN Arrowhead to the 70s elsewhere, with the Duluth forecast of 72 at the airport being the coolest day of July (coolest since 71 on June 29) - and it'll even be 66 near the lake! Gradually warming up through mid week as an area of high pressure builds in.

Late-week there will be a broad upper level ridge over the western CONUS and a deep-level trough over eastern Canada and the northeast leading to northwesterly flow aloft for the Upper Midwest. In this northwesterly flow there will be a few weak mid-level impulses with increasing low level temps in the westerly flow at low levels. This will lead to a few chances for precipitation late week into next weekend. Timing is tough to nail down due to the range in guidance, but generally most scenarios look to be light/limited precip and no strong signal for organized severe storms. Precipitation amounts at best are likely less than quarter inch over the weekend (70-85% of ensemble guidance). Highs back into the upper 80s and low 90s Saturday and Sunday, and Heat Advisories will likely needed for parts of the Northland.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 117 PM CDT Mon Jul 20 2026

VFR conditions today turning MVFR tonight as a cold front brings low-level MVFR stratus from north to south through late Tuesday morning or perhaps later. Strong west winds today gusting to 20-30 knots will persist through this evening, turning northwesterly to north overnight into Tuesday but remaining gusty through the night. A brief shower/storm is possible at INL this afternoon, and an even lower probability for a very brief storm at HYR this afternoon. With the stratus late tonight into Tuesday morning there may be light rain off and on, but do not anticipate any visibility restrictions.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 117 PM CDT Mon Jul 20 2026

Strong west winds today into Tuesday, from southwest today changing to northwest tonight into Tuesday, will lead to building waves and dangerous conditions for small craft. Wind gusts will be in the 15 to 25 knot range, and waves will build along parts of the south shore, especially between Duluth and the Apostle Islands.

Weaker winds through the rest of the week, generally out of the west at 5 to 10 knots through the weekend.

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

FIRE WEATHER

Issued at 117 PM CDT Mon Jul 20 2026

Strong winds are the primary fire weather concern today and Tuesday as a cold front moves from north to south tonight into Tuesday. West winds today are gusting to 20 to 30 mph, and these winds will persist into this evening and turn north-northwesterly as the cold front passes. On Tuesday gusty north winds continue, though becoming weaker into the afternoon hours as high pressure builds in towards Wednesday. Relative humidity values will only fall to 40 to 50 percent today and Tuesday, with overnight recovery to 90 to 100 percent thanks to increasing low level clouds tonight behind the front. Cooler Tuesday with highs in the upper 60s to mid 70s, and likely being the coolest day in over three weeks for most locations.

Drier Wednesday and Thursday with relative humidity values falling to the 30-40 percent range under sunny skies. Winds will be weaker, out of the northwest at 5 to 10 mph on Wednesday then out of the southwest at 5 to 10 mph on Thursday. Warmer and increasing chances for light precipitation amounts late Thursday through the weekend. While there will be rain chances, the majority of model guidance indicates for the late-week and weekend timeframe precip amounts will be less than a quarter inch (70-85% probability). With hot temps (back into the low 90s) and little precipitation, there is some signal for hot, dry, and windy conditions to develop, but confidence on approaching red flag criteria conditions is low.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory until 7 PM CDT this evening for MNZ020-034>038. WI...Heat Advisory until 7 PM CDT this evening for WIZ001>004- 006>009. MARINE...Small Craft Advisory until 1 AM CDT Tuesday for LSZ121-140>148- 150. Heat Advisory until 7 PM CDT this evening for LSZ142.