Thunder Bay’s three-day forecast calls for highs near 27°C, afternoon showers and thunderstorm risks Wednesday and ThursdayTHUNDER BAY – WEATHER – Thunder Bay is starting Wednesday with cool, damp conditions before temperatures climb into the upper 20s this afternoon. Today’s Weather OverviewCurrent ConditionsAt 6:00 a.m. EDT on Wednesday, July 29, the temperature at Thunder Bay was 12.9°C. Three-Day Thunder Bay ForecastWednesday, July 29Thunder Bay will see a mix of sun and cloud today. There is a 30 per cent chance of showers this afternoon, along with a risk of a thunderstorm. There is a 40 per cent chance of showers from late morning through the afternoon, with a risk of thunderstorms.