textproduct: Duluth

KEY MESSAGES

- Lingering light rain will slowly decrease in coverage and slide east through the day today. - Dangerous swimming conditions expected for the beaches of the Twin Ports today through Monday. - Unseasonably cool temperatures overnight may lead to frost formation inland beginning Sunday night and continuing through Wednesday night.

DISCUSSION

Issued at 248 AM CDT Sat Sep 19 2026

Early this morning, our primary weather concerns are widespread stratus, patchy fog, and light rain. The light rain, affecting mainly the southern portions of our forecast area, is being generated by a band of frontogenesis generated by a surface low over the the IA/NE border, out in advance of another over eastern Colorado. At the upper levels, an upper low moving across the Rockies is pushing shortwaves out across the plains ahead of it. This system is expected to continue to push east through the weekend. The stratus deck has expanded significantly overnight, causing earlier fog to dissipate in many areas. However, where skies briefly cleared, patchy fog remains a factor early this morning. With persistent east to northeast flow as the surface low remains to our south, expect mostly cloudy skies to dominate the day. This cloud cover will keep temperatures on the chilly side, particularly in northwest Wisconsin, where highs will only reach the upper 50s to low 60s. North-central Minnesota may see some breaks in the clouds later today, allowing temperatures to warm into the mid and upper 60s.

Moving into tonight and Sunday, the aforementioned low-pressure system will push further east, taking the light rain chances with it. However, high pressure will push in from the north, causing the pressure gradient to tighten, leading to gusty northeast winds, particularly over the western arm of Lake Superior. This will usher in a cooler and drier airmass. The persistent northeast flow on Sunday will keep conditions brisk and cool, especially near the lake. This will also cause clouds to persist, though there may be enough gaps for some peeks at sunshine.

Beginning Monday and continuing through the upcoming week, high pressure will firmly establish itself over the Upper Midwest and Great Lakes region. This will lead to a prolonged period of quiet, dry weather. The main story will be the cool overnight temperatures under clear skies and light winds, which may cause frost development each night from Sunday night through Wednesday night, especially for inland areas of northern Minnesota and northwest Wisconsin. High temperatures will gradually moderate as the week progresses, returning to near-normal values in the mid-to-upper 60s by late in the week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 620 AM CDT Sat Sep 19 2026

MVFR to IFR ceilings are present across the Northland early this morning and will affect the terminals much of this TAF forecast period. Due to the stratus draped across the area this morning fog is very limited in coverage, there are a few sites which have dipped into VLIFR visibilities as of 11z. These poor visibilities will improve rapidly by 13z. The northeast flow will bring an area of drier air which causes ceilings to improve late this afternoon and early evening to a combination of MVFR or VFR conditions. Unfortunately, ceilings should deteriorate again beginning around mid evening, with conditions dropping to MVFR or even IFR after 06z.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 248 AM CDT Sat Sep 19 2026

We are in the midst of an extended period of east to northeast winds across Lake Superior, which is expected to continue through this weekend and at least the first half of the work week. Winds and the resulting waves will be weaker today than they were yesterday, though I anticipate a continued high risk for rip currents along the beaches of the Twin Ports today. Wind speeds increase tonight into Sunday as the pressure gradient increases, leading to northeast winds of 15 to 25 knots, with gusts potentially reaching 30 to 35 knots, particularly in the southwest arm and along the South Shore. Waves will build substantially in response, likely reaching 4 to 7 feet. Small Craft Advisories will likely be needed for most nearshore zones, and there is a 30% chance that a Gale Warning may be required for areas from Silver Bay to Duluth and along the South Shore on Sunday. Winds will slowly subside Monday and Tuesday, but will remain elevated enough to potentially warrant continued Small Craft Advisories.

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

FIRE WEATHER

Issued at 248 AM CDT Sat Sep 19 2026

Fire weather concerns remain low through the forecast period. This weekend, minimum relative humidity values will remain above 50 percent with increased cloud cover and cooler temperatures helping to keep recent moisture from rain from evaporating. Winds will generally be from the east to northeast through the weekend, becoming gusty on Sunday, with the strongest winds near Lake Superior. The cooler conditions will continue into early next week, though minimum RH values will fall into the 40 percent range Monday. Monday begins a period of no precipitation with gradually drying RH values and generally easterly winds through at least Wednesday.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Beach Hazards Statement from 10 AM CDT this morning through this evening for MNZ037. WI...Beach Hazards Statement from 10 AM CDT this morning through this evening for WIZ001. MARINE...None.