textproduct: Duluth

KEY MESSAGES

- Widespread frost and freeze conditions are expected tonight. Additional frost and freezing temperatures are possible again Friday night.

- Light rain is expected Saturday into Saturday evening, especially along the International Border.

- Another widespread frost/freeze is expected Sunday night into Monday morning.

DISCUSSION

Issued at 132 PM CDT Thu Oct 1 2026

We have some mixed cloudscapes out there this afternoon with departing mid and high level clouds over northwest Wisconsin and some incoming stratocumulus along the International Border associated with an upper-level trough. Some of those clouds will persist overnight, mainly across the Arrowhead, with clearing elsewhere. The challenge overnight is overnight lows and figuring out just how cold it will get. We will have high pressure moving in tonight, and most places should see clear skies. However, at least some pressure gradient will persist further east, keeping winds from becoming calm in parts of northwest Wisconsin and especially along the North Shore with some downslope flow. With that said, most guidance highly favors temperatures falling to around or below 36 degrees for inland areas tonight (70-90% chance) with lesser probabilities for freezing or below temperatures (40-60% up north where Freeze Warnings are already in effect and 20-50% for parts of interior northwest Wisconsin). With all that in mind, I expanded Frost Advisories to cover all zones except the North Shore, where breezy conditions will probably prevent frost there even if temperatures do get towards freezing for some places. Some places within a Frost Advisory may not see frost, like around the Brainerd Lakes or near Lake Superior. In addition, some places in interior northwest Wisconsin could see freezing temperatures, but confidence is not high enough that it will be widespread enough to warrant Freeze Warnings. All that to say, it should be cold tonight, and there will probably be some locality to frost/freeze conditions, but in general, most places will probably see some frost.

On Friday, expect quiet and sunny weather with high pressure and seasonably cool temperatures. As high pressure moves east Friday night, parts of the Arrowhead and northwest Wisconsin will still be under the influence of that with mostly clear skies and light winds. Additional frost/freeze headlines will likely be needed. Further west in north-central Minnesota, southerly winds will pick up a bit and temperatures won't be quite as cold. Frost won't be as likely as a result. Instead, expect increasing clouds with some showers moving in with an incoming shortwave trough that's expected to pass along the Canadian border. Models continue to favor an area of mainly light rain developing and targeting the International Border on Saturday with lingering showers into Saturday evening. Rainfall amounts continue to look not-so-impressive with most places picking up a tenth or two of an inch at best.

A bit of rinse and repeat going into Sunday as a cold front passes through Saturday night and we end up with cool northwest flow on Sunday. High pressure settles in Sunday night, and we'll be looking at another widespread frost/freeze. Coverage of freezing temperatures will probably be much greater compared to tonight, though some areas (like near Lake Superior) may still evade a hard freeze.

Southerly flow will likely bring warm and above normal temperatures early next week starting on Monday. Rain chances are looking pretty sparse next week, but it's possible there could be some sprinkles or light rain from time to time.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1239 PM CDT Thu Oct 1 2026

VFR ceilings are expected through the period. There is a possibility (~25% chance) that some brief MVFR ceilings could affect INL later this afternoon and evening as an area of clouds in Ontario drops south, but most observations underneath the cloud deck are VFR right now, so that's what's most likely at INL. Breezy conditions will persist through the afternoon, then winds lighten up overnight. A bit of downsloping at DLH may cause an uptick in breezy conditions again later tonight with gusts between 15 and 20 kt, lasting into Friday morning.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 132 PM CDT Thu Oct 1 2026

Breezy conditions are happening this afternoon, so Small Craft Advisories will remain in effect through this afternoon and evening. Winds will decrease this evening as high pressure moves in, but only slightly, and we will have to keep an eye on conditions along the North Shore as there will be some downsloping winds. It's possible there could be some brief 20-25 kt gusts from Grand Marais to Grand Portage later tonight into early Friday morning. Winds become light Friday into Saturday with high pressure passing through. Some showers are possible Saturday afternoon and evening. Southerly winds will become a bit breezy, then switch to westerly and northwesterly overnight and into Sunday as a cold front passes through. Expect some strong winds Sunday with gusts to around 25 kt with northwest winds. Small Craft Advisories will likely be needed.

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

FIRE WEATHER

Issued at 132 PM CDT Thu Oct 1 2026

Expect dry conditions for the rest of today and again on Friday. Unlike today, winds will be relatively light on Friday with gusts up to 10-15 mph. Min RH is expected to fall into the 30-45% range, lowest in northwest Wisconsin with high pressure in place. Fire weather conditions may be slightly elevated due to the dry air mass. As a system passes by on Saturday, expect some light rain mainly along the Canadian border, but clouds and higher moisture elsewhere. A cold front passes through Saturday night, bringing breezy northwest flow and drier conditions again on Sunday and Monday as high pressure passes through. Some slightly elevated fire weather conditions may return with RH falling to 30-45% Sunday and breezy northwest winds. Drier conditions on Monday, but with lighter winds.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Freeze Warning from midnight tonight to 9 AM CDT Friday for MNZ010-011-019. Frost Advisory from midnight tonight to 9 AM CDT Friday for MNZ025-033-034-036>038. WI...Frost Advisory from midnight tonight to 9 AM CDT Friday for WIZ006-009. MARINE...Small Craft Advisory until 7 PM CDT this evening for LSZ140>147. Small Craft Advisory until 10 PM CDT this evening for LSZ150.