A Crisp Morning Blossoms into a Sunny Day, with Weekend Warmth and a Chance of Rain
Morning Chill Gives Way to Summer Light
Thunder Bay is off to a brisk start this Thursday, with temperatures at 9.2°C as of 7:00 AM, under partly cloudy skies. There’s a full blanket of moisture in the air with 100% humidity and a matching dew point of 9.2°C — it’s about as saturated as the morning dew gets. Winds are calm at 4 km/h from the southwest, making for a peaceful, quiet start to the day. Visibility is excellent at 32 km, perfect for enjoying the lake and Sleeping Giant views.
The barometric pressure sits at 102.1 kPa but is slowly falling, hinting at a gradual weather shift ahead. However, today will be bright and beautiful with mainly sunny skies and a high of 21°C. The UV index will soar to 9, considered very high, so lather up with sunscreen before stepping out and keep those sunglasses handy.
Tonight and Friday: Clouds Gather, But Still Comfortable
Tonight will see increasing cloud cover, with skies turning cloudy overnight. Winds will become easterly at 20 km/h, ushering in a slightly milder night with a low of 11°C.
Friday will start off cloudy, but the sun will make a comeback by the afternoon with a mix of sun and cloud. The temperature will climb to a pleasant 23°C, and with a humidex of 26, it’ll feel just warm enough to remind you summer’s in full swing. Winds will start east at 20 km/h, becoming light by noon. The UV index remains high at 7, so you’ll still want sun protection if you’re heading outdoors. Friday night will bring cloudy periods, and another mild low of 11°C.
Weekend Outlook: Partly Cloudy with Rain in the Wings
Saturday is expected to bring a mix of sun and cloud, with a comfortable high of 22°C — perfect weather for outdoor activities. However, cloudy periods return Saturday night, along with a 30% chance of showers, and a low of 10°C.
Sunday continues with a mix of sun and cloud, and a 30% chance of showers, but also a warmer high of 25°C. Sunday night may get a little wetter, with 40% chance of showers, and an overnight low of 15°C — our warmest night in the current forecast.
What to Wear: Layers Early, Light by Afternoon
Start the day in a jacket or hoodie, but by midday you’ll be switching to light, breathable clothing. With that high UV index, a hat and sunscreen are strongly advised. As we head into the weekend, be prepared for on-again, off-again clouds, so a light rain jacket or umbrella might come in handy, especially Saturday night through Sunday.
Weather History & Local Insight
On this date in Thunder Bay history, the record high was a toasty 31.3°C (set in 1980), while the record low hit 2.0°C way back in 1963. With today’s high of 21°C, we’re landing comfortably in the middle — no extremes, just good, livable weather.
Did you know? Thanks to its location on Lake Superior, Thunder Bay often experiences “lake-modified” weather — cool mornings and mild afternoons are part of the charm. It also gives you more dramatic sunsets and some of the clearest summer skies in Northern Ontario.