Marine Weather and Tide Forecast for Marquette, MI

DISCUSSION
Issued at 313 PM EDT Sat Oct 17 2026

Not a cloud in the sky this afternoon as the UP is sandwiched between expansive high pressure that extends from the lower Midwest down through the southern Plains and deepening low pressure east of Edmonton, Canada. The tight pressure gradient draped across the Upper Midwest and a 35-45 kt 850 mb LLJ has created elevated SW wind gusts between 20-30 mph with a few gusts between 30-40 mph in the Keweenaw. Very dry air advection and efficient mixing into a dry airmass aloft has allowed RHs across the UP to drop into the 20s and 30s with a few locations managing to plummet as low as 15-20%.
Despite the near critical fire wx winds and RH, temps have only peaked in the mid 50s to near 60. Plus, widespread rain over the last 48 hours have helped moisten short time-lagged fuels as well as curtail fire spread on the Rugged Terrain Complex. So, there may be a limited fire weather risk but high to extreme fire danger is not anticipated. A similar setup presents itself tomorrow as a sharp trough and aforementioned Canadian low pressure works across northern Ontario, bringing another day of WAA and gusty SW winds.
850 mb temps near 14-16C will allow temps to rise a bit warmer tomorrow, reaching the low 60s. Stronger mid-level flow between 40- 50kts should kick up winds between 25-35 mph UP wide. Latest NBM guidance suggests 50-90% chance for gusts >40 mph in the Keweenaw and downsloping locations of the western and central UP by the early afternoon. Area soundings suggest similar mixing into a dry airmass aloft, so if RHs manage to fall as low as they have this afternoon, a more elevated fire weather risk may present itself.

Winds will lighten Sunday evening, and continue to remain light through at least Wednesday morning thanks to another strong surface high migrating across the northern Plains toward eastern North America. Airmass aloft will stabilize, with 850mb temps generally remaining between +5 and 10C, varying by model. This should yield daytime highs peaking in the mid 60s for most interior locations and closer to 60F lakeside, and maybe upper 50s in the Keweenaw.
Overnight lows most nights in the 30s should be expected inland, with 40s by the lakeshores. Next best shot of rain, albeit probabilities are currently low, comes late Wednesday into Thursday.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/
Issued at 733 PM EDT Sat Oct 17 2026

Southwest winds will become less gusty but remain at around 10-15 kt sustained at the terminals overnight as the boundary layer stabilizes. Low level wind shear will develop this evening and persist tonight through 13-16z Sun morning as a strong low level jet crossing Upper Michigan brings southwest winds of 45-50 kt at FL015- 020. Winds become gusty again at the surface Sun morning through Sun afternoon, finally starting to diminish near the end of the TAF period. Other than ongoing wind concerns, expect VFR conditions under mostly clear skies through the period.

MARINE
Issued at 313 PM EDT Sat Oct 17 2026

Lake Superior: Gusty SW winds are present with the greatest gusts seen in the western half. A few gales to 35 kts have been noted on elevated platforms. Breezy conditions persist overnight below gales.
A near copy of today occurs tomorrow, however, gusts may be a bit more elevated with gales between 35-40 kts (50-90% chance, highest near Isle Royale) in the western arm of the lake. Sig wave heights build between 10-14 ft between the Keweenaw and Isle Royale through the morning and afternoon. Winds settle below 35 kts through the evening and eventually fall below 15 kts by Monday morning. Winds <25 kts are anticipated through the rest of the week.

Northern Green Bay and northwestern Lake Michigan: Gusty SW winds 20- 30 kts will be common through Sunday with a change for gales of 35 kts (30-50% chance) Sunday afternoon. By Monday, high pressure influence over the region will likely support <15kt winds through at least Wednesday.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
Gale Warning from 11 PM EDT /10 PM CDT/ this evening to 2 PM EDT /1 PM CDT/ Sunday for LSZ162.

Gale Warning from 11 PM this evening to 5 PM EDT Sunday for LSZ243-244-263-264.

Lake Michigan...
Gale Warning from 5 AM to 11 PM EDT Sunday for LMZ248-250.