Rounds of scattered showers, thunderstorms to move across southern Ontario

Southern Ontario has been blanketed by high heat and humidity with rounds of thunderstorms and rain set to move in late Tuesday.

Heat and humidity have been the name of the game this week so far, but the potential for thunderstorms and heavy rainfall stretches across southern Ontario on Tuesday.

According to CTV News London Meteorologist Julie Atchison, high heat and humidity has moved into southern Ontario this week with the humidex peaking Tuesday in the mid 30s.

Atchison says there will be scattered showers and thunderstorms Tuesday evening, prompting Environment Canada to issue some weather watches and warnings, including a heat warning in through Windsor-Essex towards Sarnia and Chatham-Kent. There is also a severe thunderstorm watch in effect in through Huron County and southern Bruce and a special weather statement is in effect through Bruce and Grey County, with the risk of heavy rainfall.

“Some of these storms have the potential to bring a whole lot of rainfall in a very short period of time,” said Atchison. “The area under the advisory could see 50 millimeters.”

In London, there’s the potential to see 10 to 20 millimeters of rainfall as rounds of scattered showers and thunderstorms continue through the evening and overnight. The low will drop to 20 C, with fog patches developing before morning.

“[The storms] will be hit and miss across the area, so there’ll be lots of the region that don’t see any rainfall at all,” added Atchison. “However, if you get under one of these storms, you’re getting a lot of rain very quickly as we head into the late evening and overnight.”

It will be a scorcher again on Wednesday, with a high of 31 C in London, feeling like 39 with the humidex. The UV will peak at nine, so make sure to cover up or wear sunscreen if outside for an extended period.

Wednesday will boast sun and cloud, but there will be a continued thunderstorm risk.

“Our weather story over the next 48 hours will include scattered showers and thunderstorms, heat and humidity, and we won’t see cooler conditions arrive until the weekend,” Atchison said.

Here’s a look at London’s long-range forecast

Tuesday night: Mainly cloudy. 40 percent chance of showers early this evening. Showers with a few thunderstorms beginning early this evening then changing to 40 percent chance of showers near midnight. Risk of a thunderstorm. Fog patches developing before morning. Local amount 15 to 25 mm. Wind south 20 km/h becoming light this evening. Low 20.

Wednesday: A mix of sun and cloud. 40 percent chance of showers early in the morning and late in the afternoon. Risk of a thunderstorm. Fog patches dissipating in the morning. Wind becoming west 20 km/h late in the morning. High 30. Humidex 39. UV index 9 or very high.

Thursday: A mix of sun and cloud with 60 percent chance of showers. High 31.

Friday: Cloudy with 40 percent chance of showers. High 27.

Saturday: A mix of sun and cloud. High 27.

Sunday: A mix of sun and cloud with 30 percent chance of showers. High 25.

Monday: Cloudy. High 21.