452
FXUS63 KDLH 191741
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1241 PM CDT Sat Sep 19 2026

.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 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 /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 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 until 9 PM CDT this evening for MNZ037.
WI...Beach Hazards Statement until 9 PM CDT this evening for WIZ001.
MARINE...None.

&&

$$

DISCUSSION...LE
AVIATION...NLy
MARINE...LE
FIRE WEATHER...LE