textproduct: Duluth

KEY MESSAGES

- Severe Thunderstorm Watch is in effect until 4 PM with a second line of storms likely to redevelop and cross the BWCA tonight.

- High heat and humidity this afternoon with heat index values over 100 degrees prompting Extreme Heat Warnings and Advisories.

- Dangerous swimming conditions persist along Lake Superior beaches due to strong rip currents through this evening.

UPDATE

Issued at 1259 AM CDT Tue Jun 30 2026

Another strong line of thunderstorms is moving through the Northland tonight, with embedded severe storms producing large hail, damaging winds, and tornadoes are still not out of the question. However, this line is moving into a less and less favorable environment, so they are expected to decrease in intensity in the next few hours.

DISCUSSION

Issued at 128 PM CDT Mon Jun 29 2026

For the rest of the day, our primary concerns will be the oppressive heat and the severe weather threat. Extreme Heat Warnings and Heat Advisories remain in effect for the southern half of the Northland. We are noting that CAMS guidance is not doing well, but there is plenty of CAPE with storms riding along a warm front. In addition, rich PWATs of 2.4+ inches giving heavy rainfall with warm sector inflow providing dewpoints in the 80s. This incredible moisture is pushing heat index values well past the 100 degree mark for many of our southern communities. Meanwhile, a Severe Thunderstorm Watch remains in effect until 4 PM for all of northeast Minnesota.

The current storm moving through St. Louis County presents itself very similar to the radar presentation of the 1999 BWCA blowdown storm with similar timing too! Thus far, this storm hasn't been too effective in bringing down winds to the surface, at least in the last 3 hours; however, the environment over NE Minnesota is rich as a little clearing occurred to allow the storm to become more surface based increasing the threat for winds as it moves through the Arrowhead. Similarly, the storm's southern end also is beginning to take on a identity of its own and should run east into the higher richer moisture. Should be an active afternoon. In addition to the storm threat, there is a wake low that is causing really strong winds in the wake of the convective line which could gust to 50 to 60 mph!

As we move into the evening and overnight hours, the threat for severe weather continues. Models continue to indicate that redevelopment is likely this evening causing a second line of storms to cross through the BWCA. Given the extreme instability and moisture in place, these storms will pose a substantial risk for large hail, damaging winds, and intense downpours capable of localized flooding. Temperatures tonight will provide little relief from the heat, with lows struggling to fall below 70 degrees in many locations.

For tomorrow, a cold front will slowly work eastward across the region. Heat Advisories will linger for our northwest Wisconsin counties as temperatures once again climb into the 90s, though drier air will slowly filter into Minnesota. Instability will pool ahead of the advancing front, bringing another round of strong to severe thunderstorms, especially during the afternoon hours across northwest Wisconsin. Large hail and damaging winds will once again be the primary hazards.

Looking ahead to Wednesday, the active summer pattern will persist. We will maintain southwesterly flow aloft as a shortwave passes through the region. This will bring additional chances for scattered showers and thunderstorms, some of which could be strong given the lingering instability. Temperatures will remain quite warm, generally in the 80s to near 90 degrees, ensuring the humid feel sticks around the area.

For Thursday through the upcoming weekend, broad ridging will remain anchored to our east with troughing to the west. This setup keeps the Northland in a warm and active southwest flow regime. Expect daily chances for showers and thunderstorms, particularly during the afternoon and evening hours. High temperatures will remain somewhat steady in the 80s. While not every day will be a washout, anyone with outdoor holiday weekend plans should monitor the forecast closely.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1238 AM CDT Tue Jun 30 2026

A line of storms continues through the Northland. Conditions at HIB and INL are expected to quickly improve after 06Z as the line passes. DLH has yet to get the worst of the line, and will pass through in the next few hours. Due to the northeast trajectory of the storms, they are currently not expected to impact HYR, but may need to be amended if the line builds to the south. Otherwise conditions will return to VFR for the remainder of the night at all terminals except DLH, which could see fog and low stratus move in from Lake Superior as was seen earlier Monday. Winds will increase out of the southwest today, with gusts to around 20 kts by the afternoon.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 1259 AM CDT Tue Jun 30 2026

Fog has cleared in the near shore waters for the time being from the line of storms moving through. However, fog is expected to redevelop and cause visibilities less than a mile into the morning. Winds out of the southwest will be 15 kts or less for the next couple days.

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

FIRE WEATHER

Issued at 1259 AM CDT Tue Jun 30 2026

Today will be the driest day this week with RH in the 35-45% range this afternoon. Hot temperatures and high dewpoints are expected to linger, particularly in northwest Wisconsin. This will only be a brief relief for Minnesota, though, as hot temperatures and high dewpoints are expected for the remainder of the week. Winds will be out of the west to southwest for the mid week, with gusts to around 20 mph.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...Heat Advisory until 7 PM CDT this evening for WIZ002>004-008- 009. MARINE...Dense Fog Advisory until 8 AM CDT this morning for LSZ121- 140>148-150.