textproduct: Duluth

KEY MESSAGES

- Lingering heat today through Friday with a bit less humid conditions. Heat Advisories may still be needed through the remainder of the week.

- Near-critical fire weather conditions are possible today. Smoke is expected to bring poor air quality to most of the region into at least Thursday.

- Better chances for showers and thunderstorms arrive Thursday into Friday.

- Very limited visibility on Lake Superior with a dense marine smoke advisory in effect for the ongoing wildfire smoke.

UPDATE

Issued at 255 AM CDT Wed Jul 15 2026

The frontal boundary that worked southward overnight has setup across central Minnesota and into northwest Wisconsin. This is seeing a decreasing in dewpoints from north to south, with this trend forecast into today. A line of non-severe thunderstorms has formed on the northern periphery of this boundary early this morning and is forecast to continue from Bemidji to Duluth into the commute hours...slowly moving southward into the Brainerd Lakes in this time. This frontal-associated convection is shown to die off by mid-morning today in high-res guidance. Towards the afternoon hours today, there is a 10-20% chance of high- based rain showers and skirting the International Border. Any precipitation is expected from a tenth of an inch or less in localized spots into this afternoon. Given the uncertainty in coverage and amounts of rainfall from these afternoon showers, there are minimal locations that have actual rain showers mentioned in the determinitistic forecast though.

Daytime temperatures today and Thursday were cooled up to a few degrees for the smoke moving southward and helping to dampen the daytime MaxTs for most areas. This resulted in a South Shore counties being dropped from the Heat Advisory and Sawyer County being changed to a Heat Advisory today in place of the previous Extreme Heat Warnings. All other Heat headlines remain in place.

Light winds under 10 mph are expected today as minimum relative humidity down to 28-38 percent is forecast. A Special Weather Statement was issued for the Iron Range and northward in far northern Minnesota to continue to highlight a possible near- critical fire weather potential this afternoon and evening given these moderately dry conditions after the last few days of critical fire weather conditions.

There remains a 20-30% chance of rain showers north of the Iron Range late Wednesday night into Thursday morning, but mainly west of US Hwy 53 for the Borderlands. The much higher rain chances east of US Hwy 53 into the interior Arrowhead begin Thursday night when a quarter-inch to half-inch of rainfall is forecast by Friday evening.

The previous Air Quality Alerts from MNPCA and WiDNR remain in effect as they were last evening. Smoke is modeled into all parts of the region except northern Itasca County and Koochiching County today. The latest air quality current conditions and forecasts can be found on the MNPCA website and the WiDNR websites to help keep informed about the coming days air quality conditions.

DISCUSSION

Issued at 304 PM CDT Tue Jul 14 2026

High pressure was centered over the Mid-Mississippi Valley early this afternoon and extended eastward to the Mid-Atlantic. It also stretched northwestward into the Northern Plains and Canadian Prairies. A cold front extended from northern Quebec southwestward across southern James Bay, northwestern Ontario, and into northern Minnesota and North Dakota. This front will move south this afternoon and into tonight before stalling out across central Minnesota and northern Wisconsin. There isn't a strong push of cooler air behind the front, but winds will turn northwesterly as it passes and help scour out the very high dewpoints that have been in place. Ahead of the front, highs will again be in the 90s with 60s and low 70s dewpoints keeping dangerous heat conditions in place. An Extreme Heat Warning remains in place for almost all of the Northland into this evening. There remains a small chance (30% or less) of an isolated shower or thunderstorm ahead of the front. CAMs were a bit more robust with this activity overnight, but have backed off in more recent runs. However, a line of storms did develop around midday along the front, but quickly fizzled out.

Critical fire weather conditions remain in place across northern areas with dewpoints crashing in the wake of the cold front. This has dropped RH values into the 20 to 30 percent range with northwesterly winds at 5 to 15 mph. A Red Flag Warning remains in effect in this area. With the drier air continuing to push southward behind the front tonight, RH recovery is expected to be poor with values topping out in the 50-60% range north of US 2. Near-critical fire weather conditions will be seen across almost all of the Northland tomorrow with afternoon RH values falling into the 20 to 35% range. Winds will be northerly to northeasterly at 6 to 12 mph.

As winds become northwesterly behind the cold front tonight, wildfire smoke is expected to spread to the southeast over Lake Superior and then turn southwesterly across northwest Wisconsin into the Twin Ports and east-central Minnesota Wednesday. Smoke is expected to be rather thick across northeastern Minnesota and much of northwestern Wisconsin are forecast to reach Maroon (Hazardous to all) to Purple (Very Unhealthy to Everyone) levels. Air Quality Alerts have been issued for all of the Northland through at least Thursday.

The front looks to stall out across central Minnesota with northwest flow persisting aloft. As various shortwaves round the trough axis and move through the region along with upward motion across the stalled front/warm front, there will be low chances for showers and thunderstorms Wednesday into Thursday. Highs Wednesday will range from the middle 80s north to lower 90s south. With not much cooling tonight and highs again in the 90s tomorrow, have extended the Extreme Heat Warning for our southern tier of counties, aside from Price, with a Heat Advisory for the next tier north and Price County. Areas north of there do not have any headlines at this time with highs in the 80s and much less humid. Highs Thursday look similar with perhaps a bit more humid conditions to the south and additional headlines may be needed. A lake breeze is expected to develop Thursday with northeasterly winds across Lake Superior. This will keep areas near Lake Superior in the 70s and lower 80s and bring an increased chance for rip currents to Twin Ports beaches.

A stronger shortwave will propagate through the Upper Midwest late Thursday into Friday and bring an area of low pressure through the region. This will bring better chances for showers and thunderstorms during this time, but questions remain as to where the best rainfall will occur. Some models keep the best rainfall across Canada in addition to timing differences. With this package, the Arrowhead has the best chance of seeing at least 0.50 inches from this system. Beyond that, there are hints of a stronger system for the Sunday into Monday timeframe with an upper low passing to our north. Temperatures will remain above normal through the weekend in the 80s before trending closer to normal heading into next week with highs in the 70s and 80s.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 641 AM CDT Wed Jul 15 2026

Multiple rounds of wildfire smoke this TAF period bring about LIFR to MVFR visibility and IFR to MVFR ceilings. Light north to northeast winds. Scattered rain showers may skirt the International Border this afternoon and overnight with KINL the most likely to see any impacts.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 546 AM CDT Wed Jul 15 2026

Dense Marine Smoke Advisory issued for all of western Lake Superior as the smoke is being observed to create visibilities less than 1 nm. After this first round of smoke moves through the Twin Ports to South Shore, a bit of improvement in visibilities may occur this afternoon. This caused the Advisory to be split into two different segments...one ending at Noon today for Silver Bay to the Twin Ports and along the South Shore. The other parts of the North Shore though were set to end at 4 PM Thursday as there is much higher confidence in multiple periods of visibility less than 1 nm are likely.

Another issuance though could easily be needed for the Twin Ports and South Shore again tonight as model guidance helps create moderate confidence in another round of limited visibilities again this evening to tonight.

Previous Discussion 227 AM

Light winds today in the southwest arm and the Saxon Harbor under 10 knots. Westerly winds remain though between Grand Portage and Isle Royale though this afternoon and may still gust to 20 knots given the terrain funneling. No headlines are currently in effect though. Those northeast winds increase in speed for the southwestern arm of the lake Thursday and are likely to create conditions hazardous to small craft Thursday afternoon and evening. Gusts to 25 knots are forecast and waves may build to 3 feet in the Twin Ports.

Expect reduced visibility over most waters today and at least Thursday, potentially into the end of the work week as the wildfires in MN and Ontario continue.

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

FIRE WEATHER

Issued at 251 AM CDT Wed Jul 15 2026

The frontal boundary that worked southward overnight has setup across central Minnesota and into northwest Wisconsin. This is seeing a decreasing in dewpoints from north to south, with this trend forecast into today. A line of non-severe thunderstorms has formed on the northern periphery of this boundary early this morning and is forecast to continue from Bemidji to Duluth into the commute hours...slowly moving southward into the Brainerd Lakes in this time. This frontal-associated convection is shown to die off by mid-morning today. Towards the afternoon hours today, there is a 10-20% chance of high-based rain showers and skirting the International Border. Any precipitation is expected from a tenth of an inch or less in localized spots into this afternoon. Given the uncertainty in coverage and amounts of rainfall from these afternoon showers, there are minimal districts that have actual rain showers mentioned in the determinitistic forecast though.

Daytime temperatures today and Thursday were cooled up to a few degrees for the smoke moving southward and helping to dampen the daytime MaxTs for most areas. This forecast change resulted in an increase of a few percent for the afternoon MInRHs today. Even with this though, light winds under 10 mph are forecast today as minimum relative humidity down to 28-38 percent is forecast as well. A Special Weather Statement was issued for the Iron Range and northward in far northern Minnesota to continue to highlight a possible near-critical fire weather potential this afternoon and evening given these moderately dry conditions after the last few days of very hot temperatures.

Recovery RHs tonight are forecast in the 75-85% range, a notable increase from the last few days. There remains a 20-30% chance of rain showers north of the Iron Range late Wednesday night into Thursday morning, but mainly west of US Hwy 53 for the Borderlands. The much higher rain chances east of US Hwy 53 into the interior Arrowhead begin Thursday night when a quarter-inch to half-inch of rainfall is forecast by Friday evening.

Air Quality Alerts are in effect through Thursday in Wisconsin and Friday in Minnesota given the wildifire smoke.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory until 9 PM CDT this evening for MNZ025-035-037. Extreme Heat Warning until 9 PM CDT this evening for MNZ033- 034-036-038. WI...Heat Advisory until 9 PM CDT this evening for WIZ001-008-009. Extreme Heat Warning until 9 PM CDT this evening for WIZ006- 007. MARINE...Dense Smoke Advisory until noon CDT today for LSZ121-143>148- 150. Dense Smoke Advisory until 4 PM CDT Thursday for LSZ140>142.