Marine Weather and Tide Forecast for Sault Ste. Marie, MI

DISCUSSION
Issued at 314 AM EDT Thu May 21 2026

Pattern Synopsis:

A deep midlevel troughing pattern over Canada with its axis extending through the lower Great Lakes Region will continue to influence the northwoods today and Friday. Surface high pressure will keep conditions quiet through the remainder of the work week until weak upstream troughing currently over the American Rockies makes its way to the southern Midwest. Surface low pressure will follow that trough while weakening, resulting in light rainfall across the CWA around this Saturday.

Lingering low-level moisture will continue some scattered showers this Sunday before midlevel ridging builds over the southwest U.S.
and lifts northwest. Heights begin to rise Monday through the Wednesday next week, supporting subsidence aloft and surface high pressure through the remainder of the forecast period. Surface temperatures gradually warm next week as southerly air influence works its way into the northwoods as highs climb above average for late May/early June.

Forecast Details:

Today and Friday...Surface high pressure centered over the Great Lakes region will continue cool and quiet weather today. cP air influence will keep temperatures climatologically cool for late May as 850mb temps remain near freezing. Diurnal heating processes will keep highs in the 50s and 60s while overnight lows drop into the mid/upper 30s for most locations. Patchy frost remains possible tonight, favoring the typically colder areas of the CWA (higher terrain, interior), but mid/high cloud cover building from the west due to the approaching trough will hinder efficient radiational cooling tonight.

Saturday and Sunday...Aformentioned troughing building this weekend will return light stratiform rainfall Saturday. Highest probabilities in QPF remain around a quarter inch or less for most of the CWA with relatively uniform coverage. Profiles begin to dry Saturday night as low pressure progresses northeast through Saginaw Bay. Lingering low-level moisture and enough vorticity aloft will support widely scattered showers this Sunday, but little to no additional measurable rainfall is expected at this time.

Monday through Wednesday... 500mb ridging over the southwest builds across the central U.S. early next week. This pattern will support a southerly air influence moving into the Great Lakes Region combined with subsidence aloft and returning surface high pressure. Weather remains quiet and dry through the remainder of the forecast period with minimal precipitation chances and highs in the upper 70s to low 80s.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
Issued at 615 AM EDT Thu May 21 2026

VFR conditions are expected to persist across northern Michigan through the issuance period. Mid-level clouds w/ bases around 10kft currently draped across mid-Michigan may linger into this afternoon.
East winds between 5-10 kts are anticipated for most areas into this evening with gusts to around 15 kts at times. Winds look to go calm later this evening/tonight.



APX WATCHES/WARNINGS/ADVISORIES
MI...Frost Advisory until 9 AM EDT this morning for MIZ016>018-020- 021-024>026-030>036-041-042-088-099.
Freeze Warning until 9 AM EDT this morning for MIZ022-023- 027>029-086-087-095-096.
MARINE...None.