textproduct: Duluth

KEY MESSAGES

- Temperatures in the Arrowhead and Ashland and Iron counties are or will be below freezing in the next few hours. A Freeze Warning has been issued

- Not as cool elsewhere with areas of frost possible near Lake Superior and across much of northwest Wisconsin. A Frost Advisory is in effect 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.

UPDATE

Issued at 816 AM CDT Thu May 21 2026

Opted to go with a small craft and beach hazards statement for the Twin Ports. There's a pretty good signature for 25+ kt winds on the HRRR which typically pans out. HREF also has a 50+% chance of 20kt or greater sustained winds.

UPDATE

Issued at 227 AM CDT Thu May 21 2026

Early this morning, temperatures are already dipping below freezing in the Arrowhead and Ashland and Iron counties, and a Freeze Warning has been issued in these areas. The Frost Advisory is also still in place for the majority of the rest of northwest Wisconsin and up into the Iron Range.

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 /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 607 AM CDT Thu May 21 2026

VFR conditions are expected for the TAF period. Winds up to 15 kts are expected this afternoon with light and variable winds for this early morning and tonight.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 227 AM CDT Thu May 21 2026

High pressure passes to the south, keeping variable winds at 10 knots or less through early this morning. Winds will become easterly today at 5 to 15 knots. Winds will strengthen from the northeast on Friday and Friday night, reaching 15 to 20 knots with gusts up to 25 knots. This will be accompanied by waves to 2 to 4 feet along the North Shore. A Small Craft Advisory 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 227 AM CDT Thu May 21 2026

Winds are light early this morning but will become southerly at 10 to 20 mph today. Afternoon relative humidity will fall to 25 to 35 percent across the region. Another lake breeze is expected off Lake Superior this afternoon, causing an abrupt wind direction change possibly accompanied by an isolated strong wind gust. These dry and breezy conditions may lead to near-critical fire weather today. Winds become east to southeast on Friday with similar gusts. RH will again range from 25 to 35 percent in the afternoon, but our southwest areas could see RH rise in the early evening as a rain system approaches.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Beach Hazards Statement from 4 PM CDT this afternoon through this evening for MNZ037. WI...Beach Hazards Statement from 4 PM CDT this afternoon through this evening for WIZ001. MARINE...Small Craft Advisory from 4 PM this afternoon to 10 PM CDT this evening for LSZ144-145.