Sault Ste. Marie Weather Forecast – A Windy Mix of Sun and Cloud
Morning Sunshine Fades to Afternoon Clouds
Sault Ste. Marie, ON – Wednesday, May 21, 2025: It’s a brisk but manageable start to the day in the Soo, where spring is trying its best to behave. As of 6:00 AM at the Sault Ste. Marie Airport, the temperature is sitting at 9.1°C under mostly cloudy skies. The air feels crisp, with humidity at 58%, and a steady east-northeast wind blowing at 22 km/h — breezy enough to make you reconsider wearing that wide-brimmed hat. The barometric pressure sits at 101.4 kPa and is falling, which suggests unsettled weather may be around the corner.
Today’s forecast starts with a mix of sun and cloud, but don’t let that tease fool you — clouds will thicken by the afternoon. Winds are expected to ease briefly mid-morning before shifting northeast again and picking up to 20 km/h later today, with gusts reaching up to 40 km/h. The high will rise to a pleasant 17°C, a solid spring scorecard for the Soo. With a UV index of 7, you’ll want to slap on some sunscreen during those sunnier hours.
Light Showers Possible Overnight
The skies turn mainly cloudy tonight, with a 30% chance of showers popping up overnight. Winds from the northeast will continue at 30 km/h, but calm down after midnight. Overnight temperatures are expected to dip to a cool +3°C, so an extra blanket might be in order.
Thursday & Friday: Cooling Off with Spotty Showers
Thursday will be cloudy with a 30% chance of morning showers, and temperatures will top out at a cooler 12°C. Winds will do a 180, shifting to come from the northwest at 30 km/h, adding a chill to the air. The UV index moderates to 5, so there may still be some peeks of sun between the clouds.
Thursday night sees cloudy periods and a 40% chance of showers, with the temperature dropping to +2°C. Friday continues the trend with a mix of sun and cloud, but a 60% chance of showers hangs in the balance. The high will again reach 12°C, with Friday night dipping to +1°C under partly cloudy skies and a lingering 30% chance of showers.
What to Wear?
Today’s outfit of choice: light layers with a windbreaker to keep that gusty northeast breeze at bay. Sunglasses are useful early, but keep an umbrella handy later — spring in the Soo likes to keep you on your toes. A waterproof jacket will serve you well heading into Thursday and Friday.
Historic Temperatures for May 21
On this day, Sault Ste. Marie has seen a record high of 29.6°C, offering a glimpse of what late spring can deliver when it’s feeling generous. The record low? A chilly -3.2°C — thankfully, we’re nowhere near that frost zone today.
Algoma District Weather Trivia
Did you know that Sault Ste. Marie often experiences microclimates due to its proximity to both Lake Superior and Lake Huron? The shifting lake breezes can turn sunny skies into surprise showers — or vice versa — with barely a moment’s notice. It’s part of the fun (and mystery) of northern Ontario weather!
