textproduct: Duluth

KEY MESSAGES

- Becoming very hot and muggy this weekend into early next week. The most dangerous combination of heat and humidity is expected on Sunday and Monday. Several periods of Heat Advisories and Extreme Heat Warnings will likely be needed.

- Isolated to widely scattered rain showers and thunderstorms are possible the rest of today into early evening and on Saturday. An isolated thunderstorm this afternoon and evening could be strong with brief gusty winds and small hail, most likely in the Brainerd Lakes area.

- Minimal precipitation in the extended forecast. The lack of rain and fairly low relative humidities combined with the very hot temperatures on Sunday through Tuesday could lead to fire weather concerns in portions of northeast Minnesota.

DISCUSSION

Issued at 325 PM CDT Fri Jul 10 2026

Rest of Today - Tonight:

A diurnal cumulus field has developed across much of the Northland away from Lake Superior this afternoon alongside mainly light winds. High temperatures top out in the low to mid 80s this afternoon, with slightly cooler conditions immediately near Lake Superior. Low pressure moving through northwest Ontario today will bring a weak cold front into portions of north-central/far northern Minnesota by this evening. Forcing from this front and aloft should be rather nebulous as 500 mb heights will continue rising aloft. This sets the stage of a low confidence scenario for isolated to very widely scattered shower and thunderstorm development this afternoon into evening due to the weak forcing, and have kept PoPs in the 10-35% range to reflect this. Best potential for any storms to develop would be in the Brainerd Lakes/Iron Range/Boundary Waters areas. If storms develop, a couple of them could become strong with small hail, gusty winds, and a quick downpour in the Brainerd Lakes to Grand Rapids where 20-30 kt of effective shear and better MLCAPE of 500-1500 J/kg develops from late afternoon through early evening. Instability will be less with eastward and northeastward extent, so any storms that develop farther east and northeast are not expected to be strong.

Saturday:

A prominent upper-level ridge axis shifts into the Dakotas on Saturday with surface high pressure centered to our south and east. We see a similar situation to today develop on Saturday regarding isolated to very widely scattered thunderstorm potential mid/late Saturday afternoon and evening as some very weak, embedded forcing for ascent moves through the Northland on the eastern side of the upper-level ridge axis. An even more robust pool of MLCAPE (1000-2500 J/kg) is forecast for much of northeast Minnesota into portions of northwest Wisconsin, but effective shear will be on the weak side at 15-20 kt. Therefore, most storms that develop should be garden-variety pop-up storms, but can't rule out a couple being able to produce brief gusty winds, small hail, and localized downpours in their short lifespans.

The approaching ridge axis and southerly winds pumping in increasing temperatures and humidity will make Saturday feel hot and muggy. Expect high temperatures in the mid-80s to near 90 degrees, hottest in north-central Minnesota, along with dewpoints in the mid to upper 60s. Wet Bulb Globe Temperatures (WBGTs) also rise into the 79-83F range. Given the combination of hotter temperatures/humidity and higher WBGTs, a Heat Advisory has been issued for much of northeast Minnesota inland from Lake Superior where confidence in the overlap of hottest and most humid conditions are expected. Can't rule out expansion of the Heat Advisory into northwest Wisconsin on Saturday, but confidence was not as high there with this forecast update.

Sunday - Tuesday

For Sunday into early next week, deterministic and ensemble model guidance is in very good agreement for the upper-level ridge/high pressure to be over the northern Plains and Upper Midwest, largely keeping precipitation chances north of the International Border and introducing even hotter temperatures and muggy conditions to the Northland. We are looking at high temperatures each of these days in the upper 80s to mid 90s, with some pockets of upper 90s for highs possible in far northern Minnesota on Sunday and Monday. Some of these temperatures could approach or exceed record daily highs and warm lows; see the "Climate" section below for more details. Temperatures should be slightly cooler near Lake Superior each day. Dew points in the mid 60s to low 70s are also forecast for Sunday and Monday, and should drop into the upper 50s to 60s on Tuesday as a weak cold front moves through the region. WBGTs of 80-85F are also forecast each day, peaking in the late mornings through early evenings. Given this dangerous heat, an Extreme Heat Watch was issued for much of northeast Minnesota on Sunday, with additional periods of Heat Advisories and Extreme Heat Watches likely to be needed on Monday and possibly Tuesday. Overnight lows only dip into the mid 60s to low 70s each night in the early portion of next week, so limited recovery and relief from the heat is expected overnight, particularly for those without access to proper cooling or air conditioning.

As of now precipitation with the cold front on Tuesday is forecast to be minimal to zero (10% chance or less for rain) as the better forcing is favored to be north of the International Border. Therefore, several days with this heat and lack of rain, fairly low afternoon relative humidities (35-50% on Sunday and 25-45% on Monday and Tuesday), and breezy southwesterly winds for the Sunday-Tuesday timeframe may lead to fire weather concerns, especially in the Boundary Waters and far northern Minnesota where afternoon relative humidity will be the lowest. We will need to monitor forecast trends for this period closely regarding any need for fire weather headlines.

Mid to Late Next Week:

There is some indication in mid-range deterministic and ensemble guidance for the axis of the ridge to retrograde westward during the Wednesday-Friday timeframe of next week, which would offer a slight reprieve to the hottest and most humid conditions in the Upper Midwest and some low-end precipitation chances (10-40%) should that come to fruition and allow a few weak disturbances to move through our region. However, confidence in the upper- level pattern for the Upper Midwest remains lower for the latter half of next week and any precipitation chances or less hot temperatures will be dependent on whether or not the upper- level ridge axis shifts west of our region in that timeframe.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 611 PM CDT Fri Jul 10 2026

VFR conditions through the forecast period. Diurnal cumulus will fade this evening and return in the late morning hours tomorrow. A few showers will be possible with an isolated storm, but chances look to be around 15-20%. Light and variable winds this evening will switch to out of the southwest tomorrow afternoon.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 325 PM CDT Fri Jul 10 2026

East to northeast marine winds of around 10 kt continue through the remainder of today and become calm tonight with waves less than 1 ft. Can't rule out some patchy dense fog potential again tonight into Saturday morning for portions of the North Shore to Twin Ports, but confidence is low. Mainly light winds are in store for Saturday out of the south to southwest, but could be sustained around 10 kt with gusts to 15 kt near Grand Portage Saturday afternoon and evening. Winds become stronger out of the southwest on Sunday into Tuesday, with gusts of 20-25 kt possible near Grand Portage Sunday afternoon into Sunday night and for the Outer Apostles and portions of the North Shore on Monday and Tuesday that could lead to the need for Small Craft Advisories.

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

FIRE WEATHER

Issued at 325 PM CDT Fri Jul 10 2026

Light south to southwest winds at around 10 mph or less persist through the remainder of today becoming calm to light and variable tonight. Minimum afternoon RH dips to 35-50%, recovering above 90% tonight. There is a 10-35% chance for some isolated to widely scattered showers and thunderstorms for the Northland the remainder of this afternoon and evening, but confidence in development is low. Any accumulations would be light, a couple hundredths to a couple tenths unless right under a thunderstorm in which case very localized areas could see 0.25-0.50".

Another round of isolated to widely scattered pop-up rain showers and thunderstorms is possible Saturday into Saturday evening, but any accumulations aside from directly under a thunderstorm would be minimal. Temperatures become hot this weekend into early next week into the upper 80s to mid 90s for most in the Sunday-Tuesday timeframe, but dewpoints in the 60s to low 70s are also expected for most areas, so afternoon RH should fairly consistently drop into the 30-45% range, with the chance for some particularly dry spots to reach 25% in the Boundary Waters and far northern Minnesota where the hottest temperatures are forecast to be and the least amount of rainfall has been observed over the last month. This combination of hot temperatures, fairly low min RH, and breezy southwest winds on Sunday into Tuesday could set the stage for fire weather concerns, particularly in the aforementioned areas of far northern Minnesota. Some limited precipitation chances (10-40%) could return mid to late next week, but confidence is low at this point and substantial, widespread rainfall is not anticipated.

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

CLIMATE

Issued at 325 PM CDT Fri Jul 10 2026

A period of hot temperatures and humid conditions return to the Northland this weekend through early next week. Below is a list of forecast high temperatures and warm low temperatures for sites that are forecast to approach or exceed daily records. The daily records and year(s) that they occurred are also listed.

Record High Temperatures:

Forecast Record

July 11 KHIB: 86 89 (1970 and 1966)

July 12 KINL: 96 96 (1921) KHIB: 92 91 (1969 and 1966)

July 13 KINL: 98 93 (1983) KHIB: 94 92 (1983)

July 14 KASX: 94 94 (1980 and 1969)

Record Warm Minimum Temperatures:

Forecast Record

July 12 KINL: 66 69 (1898) KHIB: 64 67 (1942)

July 13 KINL: 70 69 (2013 and 1997) KHIB: 66 67 (1997 and 1943)

July 14 KINL: 70 70 (1983) KBRD: 69 72 (1901) KHIB: 67 69 (1995)

DLH WATCHES/WARNINGS/ADVISORIES

MN...Heat Advisory from 11 AM to 9 PM CDT Saturday for MNZ010>012- 018-019-025-026-035-037. Extreme Heat Watch from Sunday morning through Sunday evening for MNZ010>012-018-019-025-026-035-037. WI...None. MARINE...None.