textproduct: Duluth

KEY MESSAGES

- Areas of dense fog are possible this morning. A Dense Fog Advisory is in effect until 10 AM for portions of central and north-central Minnesota.

- Another round of showers will spread across the region early Friday and linger into Saturday morning. The heaviest rainfall (40-60% of 1") will be south of a line from Brainerd to Sandstone to Hayward to Park Falls. - Dangerous swimming conditions expected for the beaches of the Twin Ports Friday and Saturday then again Sunday and Monday afternoons and evening.

DISCUSSION

Issued at 337 AM CDT Thu Sep 17 2026

TODAY AND TONIGHT...

Light rain lingered over northwest Wisconsin east of a line from Spooner to Mercer. Another band of showers was advancing east-southeast along the North Dakota/Manitoba border east into northwest Ontario. Between these two areas of precipitation a wedge of clear skies was found. Areas of fog are anticipated this morning as winds become light. The lowest visibility will be found over areas that received rainfall Wednesday afternoon and evening. We will monitor trends. A Dense Fog Advisory may become necessary.

The light rain over northwest Wisconsin will push out of our area by 7 AM while the northern band of showers sags southward into the Borderlands and gradually dissipates by 10 AM. Otherwise expect mostly sunny to partly cloudy skies today. Highs will reach the middle 60s along the Canadian border to the middle 70s in the St. Croix River Valley. Clouds spread northward tonight ahead of an approaching low pressure system. Rain chances will likely hold off until after 7 AM Friday due to the influence of high pressure moving eastward across southern Manitoba into northwest Ontario. More on that below.

FRIDAY AND SATURDAY...

Surface low pressure and associated shortwave trough will propagate eastward from the South Dakota/Nebraska border to near southern Lake Michigan by Saturday evening. A warm front will lift northward across Iowa to near the Minnesota border and stretch east into southern Wisconsin by Friday evening. Isentropic ascent over the warm frontal zone will produce a broad area of precipitation over southern and central Minnesota stretching into northwest Wisconsin on Friday. The influence of the northern surface high pressure will be most noticeable through reinforcing dry air from north to south undercutting the precipitation. Radar echoes are likely to over-represent the northward extent of precipitation as the dry air evaporates the rain before it can reach the ground. We continued the previous shift's concept of tightening the QPF and PoP gradient over central Minnesota into northern Wisconsin.

NBM probabilities support the tight gradient of precip and PoPs. The NBM probability of more than 1 inch of rain is maximized south of our forecast area. There is a stripe of 40-60% chance of 1 inch or more south of a line from Brainerd to Sandstone to Hayward to Park Falls. The 40% threshold for 0.5 is not much farther north and extends from roughly Pine River to Moose Lake to Mellen to Mercer. The 40% chance of a tenth of an inch extends from Walker to Two Harbors to Bayfield to Ontonagon, MI. The distance of the 40% chance of 1 inch of rain and a tenth of an inch is only about 60 miles.

Rain tapers off Saturday morning with a small portion of northwest Wisconsin seeing a 30% chance of showers into the early afternoon.

As the high and low pressure systems propagate eastward winds over western Lake Superior will turn northeasterly and strengthen Friday and remain strong Saturday. The highest wind and waves will be in the southwest arm of Lake Superior which will pose a risk of rip currents for the beaches of the Twin Ports.

SATURDAY NIGHT THROUGH NEXT THURSDAY...

Another area of surface high pressure will propagate eastward across the Canadian Prairies and northern Ontario over the weekend. Rain chances Sunday have dwindled as the next area of low pressure to our south has taken a more southerly trajectory than earlier forecasts. A few sprinkles Sunday afternoon and evening aren't out of the question.

Cooler air, clear skies, and light winds will set the stage for areas of fog and frost Sunday night and again Monday night. Lows both nights are forecast in the low 40s to middle 30s.

Temperatures Sunday through Thursday will be near normal. They will start out on the cool side of the normal range Sunday with highs in the low 60s to around 70 degrees. Temps gradually warm to the warm side of the normal range by Wednesday and Thursday with highs in the middle 60s to low and middle 70s.

A chance of rain returns Wednesday night and Thursday, although overall confidence is low at this time.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1223 PM CDT Thu Sep 17 2026

A dense cumulus field is engulfing the region this afternoon with widespread MVFR conditions. There will be pockets of scattered conditions at times but in general expect the cloud cover to persist until the evening hours. Overnight a system will be moving out of the Central Plains and is expected to cross southern MN. Cloud cover will increase across our south with some rain expected tomorrow morning for BRD/HYR.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 337 AM CDT Thu Sep 17 2026

East and southeast winds of 5 to 10 knots across western Lake Superior today. Winds veer northeasterly and begin to strengthen to 10 to 15 knots with gusts of 15 to 25 knots tonight in response to surface high pressure moving eastward across northern Ontario and developing low pressure near northeast Colorado. Wind will become hazardous for smaller vessels. Small Craft Advisories will eventually be needed. There is a chance of light rain mainly over the southern half of the waters Friday afternoon through Friday night. Winds will relax over most of western Lake Superior Saturday with the exception of the southwest arm and areas near the Outer Apostle Islands down to Saxon Harbor. Saturday night through Tuesday will see a diurnal decrease in wind speeds and gusts during the night through mid- morning and then an increase in wind speeds late morning through early evening. Additional Small Craft Advisories may be needed. There is a 20% chance of gales to 35 knots over the eastern Apostle Islands to Saxon Harbor Sunday afternoon.

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

FIRE WEATHER

Issued at 337 AM CDT Thu Sep 17 2026

No fire weather concerns. Min RHs through the forecast period remain above 40% with highs in the 60s and low 70s. Rain chances will return early Friday morning and linger into Saturday morning. Rain chances and amounts have been trending farther south with time each day. As of this morning the heaviest rain still looks to remain to our south but we do have a 40-60% chance of seeing 1" of rain from southern Pine into Price Counties. Totals taper off as you head north and there will likely be a sharp gradient as dry air from Canada undercuts some of the rain totals. Areas north of a line from Walker to Duluth to Mercer are unlikely to see measurable rain.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...None.