THUNDER BAY — WEATHER –Thunder Bay is starting Tuesday under mostly cloudy skies, with a warm and somewhat humid day ahead.
Temperatures will climb well into the mid-20s today before a cooler, more unsettled pattern arrives Wednesday. The best stretch of weather this week appears to be Thursday and Friday, when sunshine returns and daytime highs settle into the low 20s. By Saturday, another chance of showers moves back into the forecast.
At7:00 AM EDT Tuesday, August 11, the city Airport was reportingmostly cloudy skiesand a temperature of13.8°C. Humidity is high at91 per cent, with a dew point of12.4°C, making the morning feel damp and cool. Winds are light from thenorthwest at 5 km/h. Barometric pressure is101.4 kPa and falling, while visibility remains excellent at32 kilometres.
Friday is shaping up to be the best weather day of the week.
Despite the cloudy start, temperatures are expected to rise quickly through the morning and afternoon. Thunder Bay will see amix of sun and cloud today, along with a30 per cent chance of showers this afternoon. The high will reach26°C, with a humidex of29. The UV index will be7, or high, so sunscreen, sunglasses and a hat are recommended if you are spending extended time outdoors. Tonight will be partly cloudy with a30 per cent chance of showers early this evening. The overnight low will fall to12°C. Wednesday will be noticeably cooler and more unsettled. Environment Canada is calling formainly cloudy skies, with a40 per cent chance of showers beginning late in the morning and continuing through the afternoon. There will also be arisk of a summer storm during the afternoon. The daytime high will reach21°C, with a UV index of6, or high. Wednesday night will bring cloudy periods and a30 per cent chance of showers, with a low of11°C. Anyone planning outdoor work, travel or recreation should keep an eye on changing weather conditions Wednesday afternoon, particularly if thunderstorms begin to develop. Thursday brings an improvement in the weather. Expect amix of sun and cloudwith a daytime high of22°C. Skies will clear Thursday night as temperatures fall to10°C. For outdoor activities, Thursday should offer one of the more comfortable days of the forecast period, with seasonal temperatures and no precipitation currently indicated. Friday is shaping up to be the best weather day of the week. Thunder Bay can expectsunny skiesand a high of23°C. Friday night will feature some cloudy periods, with the temperature dropping sharply to8°C. That overnight temperature is slightly cooler than Thunder Bay’s normal minimum of about10°Cfor this time of August. Amix of sun and cloudis forecast, along with a30 per cent chance of showers. Saturday night will remain partly unsettled, with cloudy periods and a30 per cent chance of showers. The overnight low will be12°C. Tuesday will be warm enough for shorts, T-shirts and other summer clothing, although carrying a lightweight rain jacket or umbrella would be a good idea because of the afternoon shower risk. Wednesday will feel cooler, especially under cloudy skies. A light jacket or sweater may be useful during the morning and evening. Thursday and Friday should be comfortable for most outdoor activities, but overnight temperatures of10°C Thursday and 8°C Fridaymean campers and anyone spending time outdoors after sunset should have warmer layers available. With UV levels rated high Tuesday and Wednesday, sunscreen, sunglasses and a hat remain major even when skies are partly cloudy. The overall pattern from August 11 through August 15 is one of alternating summer warmth and cooler, unsettled periods. Tuesday will be the warmest day, reaching26°C, before temperatures dip to21°C Wednesday. Conditions improve Thursday and Friday, with highs of22°C and 23°C, before another chance of showers arrives Saturday. the northwestern Ontario hub’s normal temperatures for this period are approximately24°C for the daytime high and 10°C overnight, putting most of this week’s forecast relatively close to seasonal values. Sunrise Tuesday is at6:45 AM EDT, while sunset is at9:19 PM EDT, providing more than 14 hours of daylight. Thunder Bay’s location at the western end of Lake Superior can have a significant influence on regional temperatures. During summer, Lake Superior often moderates temperatures near the waterfront. On some days, neighbourhoods close to the lake can be several degrees cooler than inland areas, particularly when winds blow off the water. That lake influence is one reason temperatures around Thunder Bay can vary considerably over relatively short distances. Forecast information is based on Environment and Climate Change Canada observations and the forecast put out at 5:30 AM EDT on Tuesday, August 11, 2026. Weather conditions and storm risks can change quickly, so residents should monitor updated forecasts and alerts throughout the day..
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📍 Source: NetNewsLedger · By: NetNewsLedger Staff · 🗓️ August 12, 2026 · 🏠 ThunderBay.Online
