The Greater Montreal area is under a severe thunderstorm watch Wednesday, with the potential for damaging wind gusts, hail, torrential rain, and a tornado. According to Environment Canada, conditions are favourable for the development of severe thunderstorms that can produce damaging wind gusts, hail, and torrential rain. There is also a risk of a tornado. “Nautical activities may be hazardous due to sudden, severe wind gusts over bodies of water. Local utility outages are possible,” the weather agency says. “Damage to roofs, fences, branches or soft shelters is possible.” Environment Canada advises people to head indoors when thunder roars. Heavy rain can cause flash flooding and significant reductions to visibility, the agency says. The Greater Montreal area is also under a heat warning. Daytime highs are expected to be between 30 and 33 degrees Celsius from Wednesday to Saturday, with humidex values between 40 and 44.