textproduct: Duluth

KEY MESSAGES

- Widespread frost tonight away from Lake Superior with some locations falling to freezing or just below. Another round of frost expected Wednesday morning, but not as widespread.

- Persistent northeasterly winds will keep the threat for rip currents in place at Twin Port beaches this afternoon and Tuesday and may linger into mid-week as well.

- Low chances for rainfall through the forecast period.

DISCUSSION

Issued at 1246 PM CDT Mon Sep 21 2026

High pressure was centered just to the northeast of Lake Superior early this afternoon and extended across all of the Upper Midwest. Weak upper level troughing was in place as well, leading to some light shower activity across southern Minnesota per radar and surface observations. This activity is weakening as it moves north and is not expected to affect the Northland. Clearing skies are expected heading into tonight with winds becoming light and variable. Temperatures are expected to fall into the middle to lower 30s away from Lake Superior leading to widespread frost across the region. Some areas along and north of the Iron Range and across the Penokee Range may reach freezing or just below, but a hard freeze is not expected. A Frost Advisory will be needed.

As the area of high pressure moves to the east tomorrow, southerly return flow will setup across the Upper Midwest and signal the start of a slow warming trend into the weekend. Highs for the remainder of the week will be in the 60s with some upper 50s Tuesday through Wednesday along the North Shore with onshore flow expected. Lows tomorrow night will remain on the cool side in the middle to upper 30s and another Frost Advisory may be needed for areas inland of Lake Superior.

Upper ridging will setup across the central CONUS Wednesday into Thursday with a shortwave pushing eastward underneath for Wednesday night into Thursday. This may lead to some shower activity during this time, but dry air in the low levels and high pressure to the east will work against them. Additional rain chances will be possible over the weekend as another shortwave moves through, but overall chances look low. Some 70s will be possible by Sunday and Monday, mainly across northwest Wisconsin.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 621 PM CDT Mon Sep 21 2026

VFR conditions are expected for all terminals for the TAF period except for HIB. HIB may see fog late tonight, bringing conditions down to IFR/LIFR for a few hours before sunrise. Winds will increase out of the southeast tomorrow up to 15 kts.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 1246 PM CDT Mon Sep 21 2026

High pressure remains in place over western Lake Superior with the center just to the east of the lake. This will keep winds easterly today and tomorrow. The strongest winds will be in the western arm and along the South Shore both days. Small Craft Advisories remain in effect into this evening for these areas with another round possible tomorrow. Winds become more southeasterly tomorrow night before becoming more easterly once again on Wednesday. Current forecast keeps gusts just below advisory level, but if winds trend upward, another round of advisories may be needed.

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

FIRE WEATHER

Issued at 1246 PM CDT Mon Sep 21 2026

Easterly wind gusts of 15 to 20 mph will be possible near Lake Superior today and tomorrow with lighter winds inland. RH values will remain above 45% today before drier air leads to values falling into the 35 to 45% range across much of northwest Wisconsin for tomorrow. Vales will remain above 45% across most of northeastern Minnesota tomorrow. There is a chance for light showers Wednesday night into Thursday, mainly across northeastern Minnesota. A wetting rainfall is not expected for most of the area with this system.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...Frost Advisory from midnight tonight to 8 AM CDT Tuesday for MNZ010>012-018-019-025-026-034>038. Beach Hazards Statement until 10 PM CDT this evening for MNZ037. WI...Frost Advisory from midnight tonight to 8 AM CDT Tuesday for WIZ001>004-006>009. Beach Hazards Statement until 10 PM CDT this evening for WIZ001. MARINE...Small Craft Advisory until 10 PM CDT this evening for LSZ143>148-150.