textproduct: Duluth

KEY MESSAGES

- Critical fire weather conditions continue today across northeast Minnesota and a Red Flag Warning remains in effect.

- Dry conditions on Tuesday, and dry, warm and breezy conditions on Wednesday will create near critical fire weather conditions across northeast Minnesota, and potentially across northwest Wisconsin.

- Rain showers and thunderstorms return to the forecast Thursday and Thursday night. A few thunderstorms may be strong to severe.

DISCUSSION

Issued at 1200 PM CDT Mon Apr 20 2026

Critical fire weather conditions will continue across northeast Minnesota today and a Red Flag Warning remains in effect. Afternoon minimum relative humidity of 20-25 percent with wind gusts of 25 to 30 mph will continue on the western periphery surface high pressure across the western Great Lakes. Decreasing cloud cover this afternoon supports continued drying from an already dry start to the day for relative humidity.

Dry high pressure will be in place on Tuesday across the Northland, with widespread afternoon relative humidity falling to the 17 to 23 percent range which is on the drier end of the forecast envelope and closer to the HRRR solution given the relative humidity behavior observed today. Northerly winds of 5 to 10 mph will somewhat limit the fire weather threat. Still near critical fire weather conditions are expected on Tuesday with the dry air and dry fuels.

On Wednesday, return flow begins with departing high pressure and low pressure deepening across the Northern Plains. Well above normal temperatures in the lower to mid 70s are forecast across northwest Wisconsin and northeast Minnesota, with a few readings in the lower 80s certainly possible across the Brainerd Lakes area. This is highlighted well by an elevated Extreme Forecast Index (EFI) from the ECMWF Ensemble for maximum temperatures on Wednesday. With dry fuels, increasing south- southeast winds and deeper moisture yet to arrive, another day of near critical fire weather conditions is expected on Wednesday. With low pressure to the west of the region, a strong lake breeze is likely to develop off of Lake Superior with temperatures in the 50s, possibly in the 40s, near Lake Superior.

Thunderstorms return to the forecast on Thursday as moisture and buoyancy build in the warm sector of deep low pressure still across the Northern Plains. A strong cold front will move across the Northland Thursday evening and night. While the greatest shear and forcing is likely to lag the cold front, increasing mid level flow and impulses ejecting out of the closed Northern Plains low coupled with the buoyancy in place will be sufficient for a strong to severe thunderstorm threat across northeast Minnesota and northwest Wisconsin Thursday afternoon, with a greater threat with the passage of the cold front Thursday evening. If the cold front arrives sooner closer to peak heating and buoyancy, the severe thunderstorm risk will be relatively greater. ECMWF Ensemble and GEFS based machine learning severe weather probabilities highlight the Northland for a threat of severe thunderstorms on Thursday. Details in hazards, timing and coverage will be sorted out over the coming days.

In the wake of this storm system, temperatures cool back down to more normal values in the 40s and 50s for high temperatures into the weekend.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1200 PM CDT Mon Apr 20 2026

VFR conditions today with strong southerly wind gusts of 20 to 25 kts through sunset. VFR conditions are expected tonight and Tuesday as high pressure builds across the region in the wake of a cold front.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 1200 PM CDT Mon Apr 20 2026

Southerly wind gusts of 20-25 kts will create conditions hazardous to small craft this afternoon and early evening from Two Harbors, through the Twin Ports and for most of the South Shore. Waves building to 2 to 4 feet, and wind gusts to 25 kts from Grand Marais to Grand Portage will also create hazardous conditions for small craft. Small Craft Advisories are in effect for these areas today.

High pressure builds across the area on Tuesday with northerly winds around 5kts

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

FIRE WEATHER

Issued at 1200 PM CDT Mon Apr 20 2026

Critical fire weather conditions will continue across northeast Minnesota today and a Red Flag Warning remains in effect. Afternoon minimum relative humidity of 20-25 percent with wind gusts of 25 to 30 mph will continue.

Near critical fire weather conditions are expected on Tuesday with dry high pressure in place, sunny conditions and drying fuels. Widespread afternoon relative humidity of 17-23 percent is likely with northerly winds of 5 to 10 mph.

South to southeast winds increase on Wednesday ahead of developing low pressure across the Northern Plains. Well above normal temperatures in the lower to mid 70s are forecast across northwest Wisconsin and northeast Minnesota, with a few readings in the lower 80s certainly possible across the Brainerd Lakes area. A strong lake breeze is likely to develop off of Lake Superior with temperatures in the 50s, possibly in the 40s, near Lake Superior. With dry fuels, increasing south- southeast winds, and relative humidity of 27 to 34 percent, another day of near critical fire weather conditions is expected on Wednesday away from Lake Superior.

Thunderstorms return to the forecast on Thursday with increasing humidity levels with southerly winds of 15 to 20 mph. A few thunderstorms may be severe on Thursday.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Red Flag Warning until 8 PM CDT this evening for MNZ010>012- 018-019-025-026-033>038. WI...None. MARINE...Small Craft Advisory until 8 PM CDT this evening for LSZ121- 144>146-148. Small Craft Advisory until 10 PM CDT this evening for LSZ140.