Area Forecast Discussion

KEY MESSAGES

- Dangerous swimming conditions expected for the beaches of the Twin Ports today through Monday. - Frost is forecast beginning Sunday night and continuing through Wednesday night. Sub-freezing temperatures are forecast Monday night.

DISCUSSION

Issued at 144 PM CDT Sat Sep 19 2026

For the rest of the day, expect rain showers across inland northern Wisconsin. A cold front will drop southward from the north this evening and tonight, bringing a period of low cloud bases and potentially some very light and isolated rain showers. Northeast winds gusting around 20 to 25 mph at the head of the Big Lake in the Twin Ports will slowly decrease this afternoon, but they will continue to create a High Risk for rip currents and dangerous swimming conditions for Lake Superior beaches. Late tonight into Sunday, isolated lake effect rain showers are possible for the South Shore lake effect belts the limiting factor looks to be low-level instability and lapse rates are fairly limited so notable lake effect rain accumulations are not expected.

Sunday will feature an even stronger push of winds off the Big Lake, leading to another day of High Risk for rip currents for the Twin Ports beaches. A Beach Hazards Statement will again be needed for Sunday and also likely again Monday. Gusts up to 35 mph are possible for the Twin Ports and South Shore communities during the daytime so it could be somewhat windy for those recreating even onshore Sunday daytime. This setup of notable high pressure centered over southeast Canada associated producing the incoming cold front is bringing in a colder airmass, along with a much drier airmass settling over the Upper Great Lakes. Northeast Minnesota will be positioned on the far western edge of this drier and seasonably cool airmass.

Clouds will clear from northwest to southeast Sunday night, which means a small area of frost is possible for the Minnesota Borderlands and interior Arrowhead by early Monday morning. Frost headlines may be needed for these limited areas pending the exact sky cover trends over the next 24 hours. The real chill arrives Monday night as widespread frost is forecast for all areas, with pockets of sub-freezing temperatures also becoming more likely by early Tuesday morning. Frost headlines, and potentially Freeze Warnings, are likely to be needed across the region for Monday night.

These frost and low-end freeze potential chances will last right into Tuesday night as well as high pressure firmly controls our weather pattern. We will slowly begin to warm a bit by Thursday. Expect dry conditions through the early and middle portions of the week ahead. Finally, looking toward the end of the forecast period, a potential late week system will approach, bringing north-central Minnesota some low-end 20 to 40 percent chances of limited-coverage rain showers.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1237 PM CDT Sat Sep 19 2026

Stratus is clearing in far northern Minnesota early this afternoon and is forecast to continue into southern terminals towards this evening. If not clearing, at least the ongoing IFR to MVFR ceilings lift towards VFR through 03-06Z this evening. A backdoor cold front drops southward tonight and may create a few light rain showers for the Borderlands and Arrowhead into the South Shore this evening and early overnight...right now only the Int'l Falls KINL TAF has any precip mentioned for the current shower proximity this afternoon. A period of MVFR to IFR ceilings accompany the backdoor cold frontal passage tonight. Winds shift to fully north to northeasterly and increase in speed, especially for shoreline terminals Sunday daytime. Gusts upwards of 30 knots are possible Sunday daytime at Duluth Int'l KDLH TAF site.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 149 PM CDT Sat Sep 19 2026

Winds will increase significantly late tonight into Sunday morning for most of western waters. Northeast winds of 15 to 25 knots are forecast for Sunday, with gusts potentially reaching 30 to 35 knots in the southwest arm and along the South Shore. Waves will build to 4 to 7 feet. Small Craft Advisories are in effect, and a short period of gales to 35 knots is possible from Silver Bay to Duluth and along the South Shore on Sunday. Winds decrease Sunday evening, but expect lingering swell into Monday from 1 to 3 feet under continued northeast winds of 10 to 20 knots and locally gusting to 25 knots for the South Shore and southwest arm again.

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

FIRE WEATHER

Issued at 151 PM CDT Sat Sep 19 2026

Fire weather concerns remain low through the forecast period. Minimum relative humidity values will remain above 50 percent through the weekend due to increased cloud cover and cooler temperatures. Winds will generally be from the east to northeast, becoming quite gusty on Sunday near and just downwind of Lake Superior. Monday begins a period of no precipitation with gradually drying conditions through Wednesday before the next round of moisture builds back into northern Minnesota for Thursday. Cooler temperatures early next week also begin to warm again later next week into next weekend.

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

DLH WATCHES / WARNINGS / ADVISORIES

MN...Beach Hazards Statement until 9 PM CDT this evening for MNZ037. WI...Beach Hazards Statement until 9 PM CDT this evening for WIZ001. MARINE...Small Craft Advisory from 7 AM to 10 PM CDT Sunday for LSZ121- 143>148-150. Small Craft Advisory from 4 AM to 4 PM CDT Sunday for LSZ140.