textproduct: Duluth

KEY MESSAGES

- Not as cool tonight with areas of frost possible near Lake Superior and across much of northwest Wisconsin. A Frost Advisory has been issued for these areas.

- Dry and breezy conditions may lead to near-critical fire weather conditions Thursday and Friday.

- Temperatures slowly warm into the weekend with rain chances late Friday into Saturday. Well above normal temperatures arrive to start the new week.

DISCUSSION

Issued at 322 PM CDT Wed May 20 2026

High pressure stretched from Lake Superior into the Central Plains this afternoon. This was leading to light and variable winds across much of the Upper Midwest. Some lingering cumulus was observed on satellite over the region, but an overall diminishing trend was seen and is expected to continue into tonight. Lows tonight are not expected to be as cool as last night, with the coldest temperatures expected around Lake Superior and into northern Wisconsin. With lows in these areas ranging from 33 to 38, areas of frost are likely to develop and a Frost Advisory has been issued.

High pressure shifts east of the Northland tomorrow over the Great Lakes with southerly return flow developing across the Upper Midwest into the Northern Plains. This will bring warmer air into the Northland with widespread 60s expected. With easterly winds, a lake breeze is expected to push inland along the North Shore and into the Twin Ports, keeping highs there in the 50s. Afternoon RH values will fall into the 25 to 35% range over much of the Northland with south-southeasterly winds of 10 to 20 mph. Current forecast is on the lower end of guidance for afternoon RHs, but with the breezy winds, better mixing conditions may lead to RHs trending lower, possibly leading to near-critical fire weather conditions. Friday looks very similar with widespread 60s away from Lake Superior and a lake breeze keeping areas near the lake along the North Shore and Twin Ports in the 50s. Winds will be southeasterly at 10 to 20 mph, but moisture is expected to increase ahead of an approaching system, which may help to keep fire weather conditions in check.

A longwave trough will move through the middle of the country for the weekend with low pressure passing to the south of the Northland. This will spread rain showers across the area for Friday night into Saturday night. A few rumbles of thunder cannot be ruled out across northwest Wisconsin, but no strong or severe storms are expected. A few showers and isolated thunderstorms may linger across northwest Wisconsin on Sunday. Saturday will be a bit cooler with 50s and lower 60s for highs as the lake breeze pushes further inland. Temperatures then turn sharply warmer starting Sunday as an upper ridge starts to build in. Highs Sunday will reach into the 60s and 70s with 70s and 80s for Monday and Tuesday. Northwest flow aloft will remain in place ahead of the ridge axis, so there will be a few chances for rainfall during this period, but overall chances will be low and mainly during the afternoon and evening hours. Temperatures look to remain well above normal heading into mid- week as well.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 614 PM CDT Wed May 20 2026

VFR conditions will prevail through the period. High pressure is currently located over the region. Clouds are expected to return Thursday morning as the high shifts to the east and southerly flow takes hold. Winds will be light and variable tonight 5 knots or less before turning southerly and increasing to 5 to 10 knots in the morning.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 322 PM CDT Wed May 20 2026

No marine concerns are expected through Thursday night. Winds tonight into Thursday morning will be variable at 10 knots or less as high pressure passes to the south. Winds turn easterly on Thursday at 5 to 15 knots, strongest at the head of the lake. Winds diminish Thursday night before increasing to 10 to 20 knots from the northeast with gusts to 25 knots at the head of the lake and along parts of the North Shore. This may lead to conditions hazardous to small craft during the afternoon and early evening hours. Higher waves may linger into Friday night before subsiding. Rain showers will spread in for Friday night and Saturday.

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

FIRE WEATHER

Issued at 1231 PM CDT Wed May 20 2026

Winds will remain light and variable this afternoon and tonight under high pressure. Minimum relative humidity this afternoon will drop below 30 percent for much of the Northland, with some areas seeing below 25 percent in northeast Minnesota. A lake breeze will move inland from Lake Superior early this afternoon, leading to a quick wind shift, a shot of cold air, and rising relative humidity values in a short amount of time. Fire weather concerns significantly increase on Thursday. Gusty south winds up to 20 mph will combine with minimum relative humidity values falling to 25 percent. The most critical conditions are expected from the northern border southward through the Brainerd Lakes. Moisture returns by Friday, bringing humidity values above 30 percent.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Frost Advisory from 1 AM to 8 AM CDT Thursday for MNZ012- 019>021-037. WI...Frost Advisory from 1 AM to 8 AM CDT Thursday for WIZ001>004- 008-009.