Lake Superior Keeps Its Cool Grip on Thunder Bay as Fog and Showers Dominate the Forecast

THUNDER BAY – WEATHER REPORT – Thunder Bay residents are waking up to damp and misty conditions as the city’s springtime seesaw continues. The chill of Lake Superior is keeping temperatures cool this morning at just under 8°C, with 100% humidity and foggy patches draping the shoreline. While the sun may make a brief appearance early today, a classic pattern of fog, drizzle, and cooler-than-average highs will linger right into the weekend.

From Fog to Showers: The Cool, Damp Forecast Ahead

At 6:00 AM EDT, Thunder Bay Airport reported mainly clear skies with a temperature of 7.7°C, matched by a dew point of 7.7°C—hence the 100% humidity and blanket of early morning fog. Winds are light from the northeast at 4 km/h, and visibility is good at 32 km outside of foggy areas. Barometric pressure is currently 100.8 kPa and falling, indicating the coming unsettled pattern.

Today will start with some sunshine early on, but the familiar springtime mix of sun and cloud will soon take over. There is a 30 percent chance of showers this afternoon, and fog patches near Lake Superior are expected to persist or redevelop late this morning and throughout the afternoon. The high will reach 18°C, but near the lakeshore it will feel noticeably cooler. The UV index will reach very high at 8, so even under hazy skies, sun protection is still a must.

Tonight will stay cloudy with a 30 percent chance of showers. Fog patches near the lake will return early this evening, and more widespread fog will develop overnight. The low will dip to 8°C.

Thursday will continue to feel more like coastal England than Northwestern Ontario—expect cloudy skies with a 40 percent chance of showers. Morning fog patches will dissipate, but they’re likely to return along Lake Superior’s shores later in the morning and through the afternoon. Winds will pick up from the east at 20 km/h in the morning, and the high will only make it to 13°C. The UV index will fall to 5—moderate.

Thursday night will bring showers and a steady low of 8°C.

Friday may finally give Thunder Bay a taste of spring warmth, with a mix of sun and cloud and a high of 20°C, though still with a 40 percent chance of showers. Friday night will see cloudy periods with a continued chance of showers and a low of 7°C.

Saturday will turn cloudy again, with a 40 percent chance of showers and a high of 16°C. Saturday night will cool further, with cloudy periods and a low of 2°C.

Sunday will bring a mix of sun and cloud but still a 40 percent chance of showers, with a cool high of 11°C. The night will finally clear up, but temperatures will dip to -1°C—yes, a frosty finish for mid-May.

What to Wear for Thunder Bay’s Foggy and Damp Stretch

Keep the layers handy—while inland areas will enjoy slightly warmer highs, areas near the lake will feel cool, damp, and misty. Rain jackets, waterproof shoes, and caution during foggy morning commutes are all part of the spring wardrobe this week.

Thunder Bay’s May 14 Weather History

The record high for this date is a balmy 28.9°C, while the record low is -2.2°C. Today’s high of 18°C is closer to the seasonal norm, but the weekend’s chilly overnight lows might once again flirt with record territory for late spring.

Thunder Bay Weather Trivia

Did you know? Thunder Bay is notorious for its spring “lake-lock” effect, where cool air from Lake Superior can keep shoreline areas foggy, cool, and damp well into May—even while areas just a few kilometers inland bask in sunshine and warmth.