NetNewsLedger Weather Desk – Thunder Bay Flash Freeze Alert

THUNDER BAY – WEATHER DESK – Thunder Bay is moving from a mild, wet afternoon into a flash freeze situation this evening, as temperatures are set to drop rapidly below freezing, turning today’s puddles and slush into ice.

At 5:00 PM EST, conditions at Thunder Bay Airport were partly cloudy with a temperature of 2.5°C, rounded to 3°C. The humidity is 67 percent, with a dew point of –3.1°C, and visibility is 24 kilometres.

Winds are light from the west-northwest at 5 km/h, and the barometric pressure is 98.8 kPa and falling, signalling that the cold front is on approach and the atmosphere is in transition.

That extra warmth today, combined with earlier precipitation, has produced wet roads, slushy snow, and ponding water — all of which are expected to freeze quicklyas the cold air surges in tonight.

Yellow Warning – Flash Freeze in Effect

Environment Canada has issued a YELLOW WARNING – FLASH FREEZE for the City of Thunder Bay.

Impact Level: Moderate
Forecast Confidence: High

What:

• Temperatures rapidly falling below freezing

• Ponding water, slush, and any new precipitation freezing into ice

• Development of widespread icy conditions on roads and walkways

When:

• This evening into tonight

Temperatures are forecast to reach the low to mid single digits this afternoon and early evening, then a sharp cold frontwill push through, causing readings to drop rapidly. Overnight lows are expected to fall to around –12°C in Thunder Bay, with flurries and strong northwest winds adding to the chill. Across the broader region, overnight lows are expected to range between –10°C and –18°C, depending on location.

That quick shift from above-zero to well below freezing, with wet surfaces already in place, is a classic setup for flash freeze conditions. Ice may form quickly and be difficult to see, especially after dark.

Tonight: Showers Ending, Flurries and a Rapid Freeze

Tonight’s forecast calls for cloudy skies with a few rain showers ending late this evening, followed by a 40 percent chance of flurries late this evening and overnight.

The wind will ramp up quickly:

• Northwest 40 km/h gusting to 60 km/h early this evening

• Easing slightly to 20 km/h gusting to 40 km/h before morning

The temperature will drop to a low near –12°C, with a wind chill near –18°C overnight.

Any water on roads, sidewalks, driveways, or parking lots is likely to freeze hard and fast, leading to:

• Icy intersections and ramps

• Slick residential streets where slush refreezes into ruts and ridges

• Very slippery sidewalks and steps, especially untreated surfaces

Drivers and pedestrians should use extreme caution. Allow extra time, reduce speed, and avoid sudden braking or sharp turns. For those walking, winter boots with good tread and slower, shorter steps will help reduce slips and falls.

Wednesday: Brighter but Cold, then Snow Returns at Night

On Wednesday, Thunder Bay will see a mix of sun and cloud. Winds will be northwest 20 km/h gusting to 40, becoming southwest 20 km/h and then light in the morning.

The high will be around –4°C, but it will feel colder:

• Wind chill near –20°C in the morning

• Wind chill near –9°C in the afternoon

That means a cold start, with surfaces still icy from the flash freeze, even as the sun peeks through.

Wednesday night, the story shifts again as another system approaches. The forecast calls for cloudy skies, with a 30 percent chance of flurries early in the evening, then snow beginning late in the evening.

Expected snowfall amounts are 5 to 10 centimetres overnight. Winds will be south 20 km/h gusting to 40, then becoming light before morning, and the temperature will rise to about –1°C by morning. Wind chills will be around –10°C in the evening, easing to –3°C overnight as the air warms slightly.

Thursday: Snow, Blowing Snow and a Sharp Drop to –21°C

On Thursday, Thunder Bay faces a full winter day. The forecast calls for:

• Snow throughout the day

• Local blowing snow

• Windy conditions

• A high near 0°C

The combination of fresh snow, wind and near-freezing temperatures will impact visibility and travel, especially on open stretches of highway and near the harbour.

Thursday night continues with snow and local blowing snow, remaining windy, and then temperatures crash again to a low near –21°C. That deep cold, combined with wind, will bring dangerous wind chills and another round of freezing and hard-packed surfaces.

Late Week: Staying Snowy and Cold

The wintry pattern continues into the weekend:

• Friday: 30 percent chance of snow, high near –13°C; 60 percent chance of snow Friday night with a low near –18°C.

• Saturday: 40 percent chance of flurries and a high near –6°C; 40 percent chance of flurries Saturday night and a low around –20°C.

• Sunday: 30 percent chance of flurries with a high near –12°C; 30 percent chance of snow Sunday night and a low near –19°C.

• Monday: 40 percent chance of snow with a high near –6°C.

In short: mild and wet now, icy tonight, then a steady stretch of snow and deep cold to close the week.

What to Wear and How to Prepare

For this evening and tonight’s flash freeze:

• Dress in warm layers: a thermal base, a mid-layer (like a hoodie or fleece), and a winter jacket that blocks wind.

• Insulated boots with good traction are important, as sidewalks and parking lots may become icy very quickly.

• A toque, mitts, and a neck warmer will help with wind chills pushing toward the minus high teens overnight and minus twenties Wednesday morning.

For drivers:

• Expect rapidly changing road conditions as temperatures drop.

• Scrape and clear all windows, lights, and mirrors.

• Leave extra space and reduce speed, especially on bridges, overpasses and less-travelled roads.

Thunder Bay Weather Trivia – Classic Flash Freeze Territory

Thunder Bay’s position along the north shore of Lake Superior puts it right in the path of sharp cold fronts sweeping in from the northwest. When those fronts arrive after a mild, wet afternoon like today, the temperature can drop quickly and turn harmless-looking water and slush into sheets of ice in just a short time.

It’s one of the reasons flash freeze warnings are taken seriously here — not because of how much falls from the sky, but because of how fast what’s already on the ground turns to ice.

The Last Word on the Weather Tonight:
Thunder Bay faces a flash freeze Tuesday evening as temperatures plunge from +3°C to –12°C, rapidly freezing slush and water into ice before snow and deep cold return.