Overview
Thunder Bay residents should expect a warm start to the week, followed by a brief shift to cooler and more unsettled conditions midweek, according to observations from the Thunder Bay Airport and forecasts issued for the region. The best stretch of weather is forecast for Thursday and Friday, when sunshine returns and daytime highs settle into the low 20s.
Tuesday: warm and humid, chance of afternoon showers
At 7 a.m. EDT on Tuesday, the Thunder Bay Airport reported mostly cloudy skies and a temperature of 13.8°C. Relative humidity was high at 91 per cent with a dew point of 12.4°C, producing a damp morning feel. Light northwest winds near 5 km/h and falling barometric pressure (about 101.4 kPa) accompanied excellent visibility at roughly 32 kilometres.
Temperatures are forecast to climb into the mid-20s, with a daytime high near 26°C and a humidex around 29. There is a 30 per cent chance of showers this afternoon and a similar chance into the evening. The UV index is expected to be 7 (high), so sunscreen and sun protection are advised for those spending extended time outdoors.
Wednesday: cooler with showers and a thunderstorm risk
Wednesday brings a noticeable change. Environment Canada is forecasting mainly cloudy skies, with a 40 per cent chance of showers beginning late morning and continuing through the afternoon. There is also a risk of a thunderstorm during the afternoon, and people planning outdoor activities or travel should monitor conditions closely.
The daytime high on Wednesday is expected to reach about 21°C, with the UV index around 6 (high). Overnight, cloudy periods and a 30 per cent chance of showers are expected, with a low near 11°C.
Late week and weekend outlook
Thursday and Friday are forecast to be the drier days this week, with sunshine returning and highs easing back into the low 20s. By Saturday, another system may bring a renewed chance of showers into the forecast.
- Early morning conditions (Tuesday): 13.8°C, 91% humidity, visibility 32 km.
- Warmest day: Tuesday, high near 26°C, humidex 29.
- Greatest precipitation risk: Wednesday afternoon, 40% chance of showers and thunderstorm risk.
Quick reference
| Day | High | Precipitation Chance | Notes |
|---|---|---|---|
| Tuesday | 26°C | 30% | Warm, humid; UV 7 |
| Wednesday | 21°C | 40% | Cooler; risk of thunderstorms |
| Thursday | Low 20s | Lower | Sun returns |
| Friday | Low 20s | Lower | Sunny |
| Saturday | TBD | Chance of showers | Another system possible |
"Environment Canada is calling for mainly cloudy skies, with a 40 per cent chance of showers beginning late in the morning and continuing through the afternoon."
Residents and visitors alike should plan outdoor work or recreation with the midweek uncertainty in mind, packing rain gear for Wednesday and keeping an eye on forecasts and any thunderstorm warnings. With UV levels still high on Tuesday and Wednesday, sun protection remains important even when skies are partially cloudy.
This forecast is based on local observations and regional guidance current as of early Tuesday morning. Weather conditions can change quickly; consult Environment Canada or local updates for the latest advisories.
