UPDATE: As of 11pm, all severe thunderstorm warnings and watches had been rescinded in all areas.
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Thunderstorms packing 100km/h winds could blow into southwestern Ontario Monday.
Environment Canada has issued a severe thunderstorm watch for London Middlesex, Oxford, Elgin, Windsor-Essex, and Chatham-Kent.
According to the national weather agency, the hot, humid conditions are favourable for the severe storms to develop in the afternoon as a cold front moves through the northwest. The thunderstorms could be accompanied by torrential downpours of 25-50mm of rain in under an hour and wind gusts of up to 100 km/h.
The strong winds could snap trees and power lines and cause damage to weaker buildings.
There is also a possibility the severe thunderstorms could produce a tornado. Last week, two tornadoes formed in Haldimand, Norfolk, and Oxford counties during intense thunderstorms.
The Office of the Fire Marshal and Emergency Management recommends that anyone outdoors take cover immediately if threatening weather approaches.
The wild weather will help bring an end to the extreme heat across the region. Forecasters expect temperatures to ease to the low to mid-20s Tuesday.