Update 8:30pm: Environment Canada has ended the severe thunderstorm watch. 

At 3:45pm, Environment Canada issued a severe thunderstorm watch, in effect for West Nipissing, North Bay, Powassan, Mattawa and French River.

Between 4:00pm and 8:00pm, there is a chance of a thunderstorm as the humidex reaches 31. According to the national meteorological service, conditions are favourable for the development of severe thunderstorms that may be capable of producing strong wind gusts and large hail.

Large hail can damage property and cause injury. Strong wind gusts can toss loose objects, damage weak buildings, break branches off trees and overturn large vehicles.

Lightning kills and injures Canadians every year. Remember, when thunder roars, go indoors!

The Office of the Fire Marshal and Emergency Management recommends that you take cover immediately if threatening weather approaches.

Severe thunderstorm watches are issued when atmospheric conditions are favourable for the development of thunderstorms that could produce one or more of the following: large hail, damaging winds, torrential rainfall.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to ONstorm@canada.ca or tweet reports using #ONStorm.

For more information: http://www.emergencymanagementontario.ca/english/beprepared/beprepared.html.