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

SHORT TERM /THROUGH SUNDAY/
Issued at 232 PM EDT Sat Jun 21 2025

An instability gradient and weakish surface trough on the southern flank of a departing shortwave over Ontario will be the focusing mechanism for a few additional shower and thunderstorms tonight - especially from the Tip of the Mitt into eastern upper. This area remains within an elongated mid level theta-e axis as well, with PWAT's greater than 1.5". Locally heavy rain will remain a threat with any showers/storms that develop. An isolated stronger storm remains possible with plenty of instability/shear in place although we are becoming increasingly capped. Any activity should gradually push north/east late tonight in response to rising heights building in from the south/west.

Otherwise, heat and humidity will be the main weather story over the next few days. Large mid/upper level heat dome builds across the eastern CONUS resulting in rising heights across the Great Lakes. At least temporarily, this will push our recent "ridge runner" convection northward into Canada. Very uncomfortable "low" temperatures tonight as high surface dewpoint air sits across the area, keeping temperatures in the 70s for many locales (a few areas could remain close to 80!).
Some patchy fog also possible, especially in areas that received heavy rain on Saturday. Hazy, hot and humid on Sunday with highs in the upper 80s to mid 90s, slightly cooler near the lakes. Combined with dewpoints in the 70s, expect triple digit heat index values in some areas. Certainly a day to stay hydrated if outside for any length of time. Winds still on the gusty side from the southwest (although not nearly as strong as Saturday). Heat advisories continue for all of northern lower.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
Issued at 232 PM EDT Sat Jun 21 2025

Active weather for much of the upcoming week. High pressure anchors itself over the southeast CONUS with a series of northern stream shortwaves pushing along the northern periphery of the upper ridge and into the Great Lakes. This will break the heat across the northern lakes and turn temperatures more seasonable by Tuesday but will put northern Michigan squarely in the path for successive shortwave energy. It will be difficult to time any one of these features given the fast flow but showers/storms will be in the forecast on most days. Locally heavy rain will also remain a threat throughout this period.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1257 PM EDT Sat Jun 21 2025

VFR conditions will gradually return to all terminals this afternoon/evening as the lower clouds dissipate. A few additional showers and storms remain possible through tonight, most likely at PLN, CIU. In these areas, conditions could briefly drop to IFR/MVFR. Patchy fog will be possible later tonight, especially at PLN, CIU. Gusty south/southwest winds into early this evening with some gusts over 30kt possible.
Winds will gradually diminish tonight.

APX WATCHES/WARNINGS/ADVISORIES
MI...Heat Advisory until 8 PM EDT Monday for MIZ016>018-020>036-041- 042-099.
Air Quality Alert from 8 AM Sunday to midnight EDT Sunday night for MIZ016-020-021-025-026-031-099.
Beach Hazards Statement through Sunday evening for MIZ020-025- 031-095-096-098.
MARINE...Small Craft Advisory until 8 PM EDT Sunday for LHZ345-349.
Small Craft Advisory until 8 PM EDT Sunday for LMZ323-341-342- 344>346.
Small Craft Advisory until 8 PM EDT this evening for LSZ321- 322.