textproduct: Duluth

KEY MESSAGES

- Areas of frost are expected early this morning for much of northeast MN and northwest WI. Frost Advisories are in effect. A few of our colder spots may experience a couple hours with temperatures below freezing.

- Widespread showers with embedded thunderstorms are expected today into tonight. Rainfall potential of 1" or greater (50-80% chance) for areas south of the Iron Range.

- Hazardous marine conditions develop late tonight into Tuesday with gale force wind gusts and high waves across western Lake Superior.

- Near-normal high temperatures in the mid 60s to low 70s for the later half of the work week with additional periods of rain chances.

UPDATE

Issued at 227 AM CDT Mon Sep 14 2026

High pressure sitting over the area early this morning, in combination with light winds and clear skies have produced excellent radiational cooling conditions. Temperatures have already fallen into the mid 30s to low 40s for much of the Northland. The Frost Advisory remains in effect until 8 AM this morning, and I anticipate several of our COOP and RAWS sites in colder locations will come in with overnight lows below 32. These should still be spotty enough to not be a widespread killing frost for vegetation, but anything exposed will be damaged. We do have cloud cover advancing towards the area from the southwest, plus moisture beginning to return to the area from the southwest and winds begin to increase in advance of our precipitation chances for later today. This should cause this precipitous drop in temperatures to stall, and we should see our minimum temperatures in the next few hours before holding still and then slowly rising.

Attention then turns to the strong low pressure system that will move across the area beginning today, and continuing through Tuesday. Today, the main warm front will push its way across the area from southwest to northeast, bringing increasing clouds this morning, then a shield of rain and embedded thunderstorms pushing from southwest to northeast from late morning through the afternoon and evening hours. The strong warm air advection with this warm front along with elevated instability is likely to produce at least a few stronger storms which may produce some small hail and locally heavy rainfall, but severe storms are not anticipated at this time. Southeasterly winds will increase significantly as the rain showers move across the area, with gusts reaching 25 to 35 mph. Tonight the wave of precipitation pushes east of the area, with rain ending for most locations by early Tuesday morning. Rainfall totals by early Tuesday morning will generally range from a half inch for the Borderlands, to three quarters of an inch or more for areas south of the Iron Range. The probability of getting more than an inch of rainfall is between 50 and 80 percent, with the highest values from central MN east into parts of northwest WI. Winds also become southwesterly tonight as the warm front progresses northeast of the area. Temperatures today will be on the cooler side with precipitation falling and the warm front not expected until tonight, so have kept highs in the upper 50s to mid 60s. Tonight will be mild, only falling into the mid 40s to mid 50s.

Tuesday, the southwesterly winds veer to west and then northwest by the end of the day as the low pressure center passes across Ontario. We should see decreasing clouds and some sunshine for the afternoon. A tight pressure gradient behind the departing system will yield strong winds, with frequent gusts of 30 to 40 mph expected across the area. These winds will gradually relax by late Tuesday afternoon. High temperatures will be slightly below seasonal normals, topping out in the low to mid 60s for most locations.

DISCUSSION

Issued at 233 PM CDT Sun Sep 13 2026

Rest of Today - Tonight:

High pressure is solidly in place over the Upper Midwest, with partly cloudy skies this afternoon due to diurnal cumulus clouds. High temperatures top out near 60F to the upper 60s, warmest in Pine County to northwest WI. A few diurnal sprinkles/very light showers are possible near the international border/tip of the Arrowhead through early evening, but little to no accumulations are expected. Daytime west to northwest winds with gusts to 20 mph become light this evening.

Calm to light winds and clear skies for most of the Northland tonight will allow for good radiational cooling. This will push low temperatures tonight into early Monday morning down into the low to mid 30s, coolest in inland northeast MN and northwest Wisconsin. The typical cold spots in inland northwest WI and northeast MN could even touch freezing or slightly below freezing for a couple hours towards sunrise early Monday morning. Widespread freezing temperatures are not anticipated, so will maintain Frost Advisories with this forecast update. Warmer temperatures in the upper 30s to low/mid 40s are expected near Lake Superior, and in the Brainerd Lakes due to increasing high cloud cover ahead of an approaching low pressure system on Monday.

Monday - Tuesday:

The high pressure will be departing to our east early Monday as a strengthening and increasingly vertically-stacked low pressure system over Montana early Monday slides northeast into southern Manitoba Monday evening and far northwest Ontario Monday night into early Tuesday. An attendant surface occluded front with this system will also be moving west to east across the Northland late Monday evening and night. Expect strong moisture advection ahead of this system/front, leading to strong isentropic ascent and widespread rain showers with embedded thunderstorms spreading from southwest to northeast across the Northland from late Monday morning through afternoon. Showers and embedded thunderstorms continue into Monday evening and night, ending from west to east as the occluded front sweeps through. While severe weather is not expected, some elevated instability (MUCAPE around 200-500 J/kg), being highest in Pine County to northwest WI, combined with marginal lapse rates aloft (6 degC/km or less) and strong bulk shear vectors in the late afternoon and evening could lead to some small hail (pea size to one-half inch). Since a surface inversion should remain in place, strong thunderstorm winds are not expected. However, gusty southeast synoptic winds increasing throughout the day will reach upwards of 35 mph in the afternoon and evening hours and accompany the precipitation.

Speaking of precipitation, the current deterministic rainfall forecast calls for amounts of 0.3-1.25" on Monday into Monday night, being lowest (0.3-0.5") north of the Iron Range, and higher along/south of the Iron Range. While most locations south of the Iron Range should top out at around or less than 1", both NBM >1" probabilities (60-80%) and HREF 24-hour LPMM highlight areas of the Brainerd Lakes and east-central Minnesota into the Twin Ports/parts of the North Shore that could see upwards of 1.5". These higher amounts would be tied to higher rainfall rates associated with any embedded thunderstorms that could lead to some ponding of water on urban surfaces. Given that these areas are not co- located with where recent heavy rains fell Friday night, flooding concerns remain low.

Expect strong west to northwest winds with gusts up to 30 to locally 40 mph on Tuesday behind the occluded front, gradually decreasing late in the day. Slightly below seasonal high temperatures in the low 60s to around 70F are forecast for Tuesday. Light winds and mainly clear skies Tuesday night as high pressure settles overhead will bring cooler low temperatures back into the area in the upper 30s to mid 40s. Can't rule out some mid-30s in the typical cold spots, but the potential for more widespread frost appears low (less than 30% chance) at this time.

Mid-Week into Next Weekend:

A primarily zonal flow pattern aloft sets up for Wednesday through the end of the work week. High pressure should keep most of Wednesday dry, though rain shower chances (10-40%) return Wednesday night. Additional precipitation chances are forecast for Friday into early Saturday as lee cyclogenesis develops a surface low and ejects it northeast. There is some uncertainty as to how far north the low pressure and its associated moisture makes it into the Upper Midwest, so have maintained the broader NBM precipitation chances of 30-55% across the region for now. Should this system take a more northern track, the Northland could be poised to get another round of much needed rainfall. NBM probabilities for >0.5" are 40-55% along and south of US-2 in northeast MN and northwest WI, with decreasing probabilities towards the International Border. Temperatures in the latter half of the work week into next weekend remain near-seasonal with highs in the mid 60s to low 70s. Lows are forecast to be in the 40s to low 50s, warmest near Lake Superior.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 104 AM CDT Mon Sep 14 2026

A weather system will bring a period of largely steady moderate rain from southwest to northeast beginning during the late morning and afternoon hours today, sliding east and out of the area by Tuesday morning. Embedded thunderstorms are possible, mainly for BRD and HYR. Light and variable winds as of issuance time will pick up out of the southeast after 13z Monday morning, getting rather blustery late this afternoon and this evening with gusts of 20-30 kt. Ceilings and visibilities are expected to deteriorate pretty swiftly to MVFR and IFR as rainfall moves in through the afternoon. Visibility to improve as rain moves back out after 00z, but the IFR ceilings to linger through 06z tonight.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 227 AM CDT Mon Sep 14 2026

Quiet conditions early this morning will quickly deteriorate today as a strong low pressure system approaches. Southeast winds will increase rapidly during the day today, with gusts rising into the 20 to 30 knot range by late afternoon and early evening, causing waves to build along the North Shore. Showers with a few thunderstorms are also expected to move across the lake this afternoon and evening. After the rain moves across the area, winds will gradually veer to the southwest and then west, increasing still farther for Tuesday morning. We have increasing confidence in gales of 35 to 40 knots for most of western Lake Superior starting early Tuesday morning and continuing into early afternoon before diminishing once again Tuesday night. The Gale Watches have been converted to a combination of Small Craft Advisories and Gale Warnings which start this afternoon, then ramp up to a Gale Warning tonight into Tuesday. Winds and waves will subside Tuesday night.

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

FIRE WEATHER

Issued at 227 AM CDT Mon Sep 14 2026

Fire weather concerns remain low through the forecast. Widespread wetting rain will move across the region today and tonight, bringing a half inch to over an inch of precipitation to many areas. There is a 50-80% chance of getting an inch or more of precipitation for areas south of the Iron Range, with lighter amounts to the north. Minimum relative humidity values will generally stay above 45 percent the next few days. Southeast winds with gusts reaching 25 to 35 mph today will shift to the west and gust as high as 30 to 40 mph on Tuesday behind a departing low pressure system. Winds will diminish for the remainder of the week.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Frost Advisory until 8 AM CDT this morning for MNZ010>012-018- 019-026-035-037-038. WI...Frost Advisory until 8 AM CDT this morning for WIZ001>004- 006>009. MARINE...Small Craft Advisory from 4 PM this afternoon to 4 AM CDT Tuesday for LSZ121-141>148-150. Small Craft Advisory from 4 PM this afternoon to 10 PM CDT this evening for LSZ140. Gale Warning from 10 PM this evening to 4 PM CDT Tuesday for LSZ140. Gale Warning from 4 AM to 4 PM CDT Tuesday for LSZ141>148-150.