Cloudy Skies, Sticky Air, and Thunder Rumbles Over the North Shore

Monday, June 30, 2025 – Morning Update from Thunder Bay Airport

Thunder Bay kicks off the last day of June with a muggy 13.1°C under mostly cloudy skies. The dew point matches the air temperature, meaning the humidity is a full 100%—yep, you can just about drink the air. Winds are a light 7 km/h from the west-northwest, and the barometric pressure is at 100.8 kPa and rising, hinting at some short-term stability… before the skies potentially get dramatic later.

Today: Thunder in the Forecast, Humidity on the Rise

Expect a mix of sun and cloud, but don’t be fooled by any brief rays of sunshine. The chance of showers is 60% this afternoon, and there’s a risk of thunderstorms rolling through as fog patches lift. The high reaches a summery 27°C, with a humidex of 32, so it’s going to feel muggy and heavy. The UV index is 8, putting it firmly in the very high zone — so pack that sunscreen even if clouds are lurking.

Tonight: Storms May Linger, Humidity Clings

The risk of showers and storms lingers into the evening with a 60% chance of precipitation. Expect partly cloudy skies overnight and a low of 16°C—mild enough for a late-night lake walk if you’re dodging raindrops.

Canada Day (Tuesday, July 1): Some Sunshine, Some Storms

The forecast for Canada Day is a toss-up. We’ll see a mix of sun and cloud, but a 40% chance of afternoon showers, again with a risk of thunderstorms. Keep the barbecue covered and have a backup indoor plan for celebrations. The temperature tops out at 27°C (humidex 31), and UV index remains very high at 8 — so slather on the sunscreen between raindrops.

Tuesday night will feature cloudy periods, with the temperature easing to a more comfortable 12°C.

Midweek Outlook: A Calm Return

• Wednesday brings a lovely mix of sun and cloud, with a comfortable high of 25°C.

• Wednesday night looks clear, dipping to 9°C.

• Thursday promises full-on sunshine and a high of 24°C — perfect lake weather if you’re extending the long weekend!

Wardrobe Tip:

Opt for light, breathable clothes and a waterproof layer nearby. With possible thunderstorms, you don’t want to be caught out in flip-flops without an umbrella! And if you’re headed to Marina Park or Hillcrest Park for fireworks on Canada Day, pack a light jacket and rain cover, just in case.

Weather Trivia:

Thunder Bay is no stranger to summer thunder — with around 30 thunderstorm days each year, June and July are peak season. Historically, some of the city’s heaviest single-day rainfall events have occurred right around the Canada Day weekend.