textproduct: Duluth

KEY MESSAGES

- Frost is expected tonight into early Monday morning for much of northeast MN and northwest WI. Frost Advisories are in effect. A couple hours with patchy temperatures around freezing are also possible early Monday morning.

- Widespread showers with embedded thunderstorms are expected Monday into Monday night. Rainfall potential of 1" or greater (40-80% chance) for areas south of the Iron Range.

- 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.

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 /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1228 PM CDT Sun Sep 13 2026

VFR conditions through at least this evening. Scattered diurnal VFR cumulus dissipate this evening. Gusty west to northwest winds to 15-20 kts today become light and variable to calm tonight with cooler temperatures. This could lead to patchy fog at HIB/HYR, but potential is too low (less than 20%) to include in the current TAFs. Winds increase and become gusty out of the southeast on Monday with increasing cloud cover in the morning from SW to NE. Widespread rain will also be building into BRD late in the current TAF period, and then overspread the remaining terminals Monday afternoon along with embedded thunderstorms.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 233 PM CDT Sun Sep 13 2026

Small Craft Advisories remain in effect for portions of the nearshore waters through late this afternoon and early evening with gusts up to 25 kts. Winds will be northwest at less than 10 kts the remainder of this evening and tonight.

Hazardous marine conditions return Monday afternoon into Tuesday as a strong low pressure system moves through southern Manitoba and northwestern Ontario, resulting in a strong pressure gradient across our region. Additional Small Craft Advisory-level winds are very likely from Monday afternoon through Tuesday afternoon. There is also a 40 to 80 percent chance for gale force wind gusts Monday night near Grand Portage and a 50-90% chance for much of the western Lake Superior nearshore waters on Tuesday morning into early afternoon. These strong winds will also build wave heights to 4 to 8 ft. Gale Watches are in effect. These winds will start out southeasterly on Monday and shift to southwesterly on Tuesday before ending as westerly late Tuesday.

Winds and waves rapidly weaken by late Tuesday evening and night and are forecast to remain 15 kts or less for Wednesday into Friday.

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

FIRE WEATHER

Issued at 233 PM CDT Sun Sep 13 2026

Fire weather concerns will remain low through the forecast period. Minimum relative humidity values this afternoon dip to 33 to 50 percent across the area under mostly sunny to partly cloudy skies, being lowest in east-central Minnesota into northwest Wisconsin. Northwest winds with gusts to 15 to 20 mph through early evening become calm to light and variable tonight. Expect chilly conditions tonight with low temperatures in the low to upper 30s for most of the area, and in the low to mid 40s in the Brainerd Lakes and near Lake Superior.

Cloud cover increases from southwest to northeast on Monday with widespread rain and embedded thunderstorms also arriving from the southwest to northeast late Monday morning/afternoon and exiting from west to east late Monday evening into early Tuesday morning. A widespread wetting rain is expected across most of the region, with rainfall amounts up to 1-1.5 inches possible (60-80% chance) in the Brainerd Lakes/east-central Minnesota into the Twin Ports and parts of the North Shore. Expect 0.5-1" for most areas along/south of the Iron Range and generally 0.3-0.5" north of the Iron Range. Southeast winds will become strong with gusts to 20 to 30 mph on Monday, shifting to the west and remaining elevated with gusts of 25 to 35 mph on Tuesday behind a cold front. Min RH on Monday afternoon could dip into the 35-45% range before rain arrives, otherwise min RH is forecast to remain above 40% for the remainder of the week with winds becoming less strong for the latter half 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 from midnight tonight to 8 AM CDT Monday for MNZ010>012-018-019-026-035-037-038. WI...Frost Advisory from midnight tonight to 8 AM CDT Monday for WIZ001>004-006>009. MARINE...Small Craft Advisory until 7 PM CDT this evening for LSZ140>142. Gale Watch from Monday evening through Tuesday afternoon for LSZ140. Gale Watch from late Monday night through Tuesday afternoon for LSZ141>148-150. Small Craft Advisory until 4 PM CDT this afternoon for LSZ146>148-150.