As temperatures climb throughout Tuesday and Wednesday, the risk of thunderstorms also increases mid week in the GTA.

Tuesday started off foggy and temperatures steadily rose throughout the afternoon, reaching a high of 27 C and a humidex of 35.

There is a slight chance of showers and thunderstorms between 3 p.m. and 5 p.m. with strong wind gusts and hail and an additional 20-40 millimeters of rain falling on already saturated ground. Passing showers are possible during the same time period across the GTA.

Environment and Climate Change Canada issued a yellow heat warning for parts of southwestern Ontario as the humidex soared into the 40s in some areas. That warning is expected to stay in place on Wednesday.

In addition, a low pressure system is moving across the plains and into the Midwest in the U.S. which is going to be a potential severe weather maker on Wednesday, bringing with it extremely unsettled conditions.

Two or three rounds of storms are expected throughout the day in the Greater Toronto Area, fueled by hot and humid conditions.

The morning commute will be both foggy and rainy. Fog will reduce visibility to less than a kilometre in some areas and an additional 40-60 millimetres of rain is expected from possible severe storms. A yellow fog advisory has been issued for Toronto and the GTA.

Expect slow driving conditions as pooling of water on roadways is likely to start off the day.

Towards Wednesday afternoon and evening, strong damaging winds gusting up to 110-130 kilometres per hour are possible. Winds at that speed have the potential to bring down tree limbs and with them, power lines so power outages are possible throughout a large portion of southern Ontario. There is an elevated tornado risk in some areas as well as the potential for hail 3-5 centimetres in diameter. That’s walnut or up to egg-sized hail which can cause significant damage.

Early morning storms will come with heavy downpours and strong winds as they pass through. There will be a break towards the middle of the day but as the afternoon approaches, storms will move into Toronto in time for the commute. Any heavy, torrential downpours later in the day have the potential to cause significant flooding for parts of the city.

The high humidity will drop on Labour Day weekend as temperatures come back down to seasonal and the skies clear out.

No inclement weather is expected as kids head back to school on Tuesday, with comfortable temperatures in the low 20s.