A severe thunderstorm watch in effect for regions in the GTA. (Graham Hughes / The Canadian Press) The summer-like conditions bringing heat to Toronto on Tuesday will be short-lived and will come at a price. Toronto residents should brace themselves for a couple of rounds of thunderstorms that will begin just after the lunch hour and then again during the evening early rush, according to CP24 meteorologist Bill Coulter. Environment Canada has issued a “severe thunderstorm watch” for the southern portion of Durham region, including Pickering and Oshawa. It is warning of “strong, damaging bursts of winds” exceeding 110 km/h and the possibility of hail. At this point there are no other weather alerts in effect for the GTA. “Large hail can damage property and cause injury. Very strong wind gusts can damage buildings, down trees and blow large vehicles off the road. Be prepared for severe weather. Take cover immediately, if threatening weather approaches. Stay indoors when a thunderstorm strikes,” Environment Canada says When will the thunderstorms begin? The city is expected to witness a dramatic turn of weather late this afternoon. “Along the day today, we will have some isolated thunderstorms in the next few hours, but nothing severe at the beginning,” Barabara Lapido, a warning preparedness meteorologist from Environment Canada told CTV News. “Just a little bit of rain, but around 5 p.m. that’s when the potential for severity is increased.” Environment Canada is forecasting a 70 per cent risk of thunderstorms in Toronto, and meteorologists say they could start at around 5 p.m. and last until 9 p.m. The main thing to watch out for is the extremely strong wind, Lapido says. “A cold front” is expected to move through parts of southern and eastern Ontario kicking off potentially long lines of thunderstorms that could affect areas from the Ottawa Valley through the GTA before heading towards London and Windsor, Geoff Coulson, a warning preparedness meteorologist from Environment Canada told CTV News. What can you do to prepare for major thunderstorms? Some of these thunderstorms produce strong wind gusts that can pick up loose objects and cause them to become dangerous projectiles that can cause significant damage to buildings, experts warn. So, the first order of business should be to secure any lawn furniture or loose objects on your property or move them indoors to keep them from flying around. Severe thunderstorm watches are issued a few hours before the storm rolls in, so experts advise keeping a weather app handy so you can keep an eye out for any alerts in your area. When is the thunderstorm expected to end? Experts say the “worst of the storm activity” is expected to move down into New York after around 9 p.m. Cooler air will flood into the region in the wake of the cold front that will drive the late afternoon storms, according to Coulter. “The temperature will drop from 25 C Tuesday afternoon to just 2 C by Wednesday morning,” he says. Thursday and Friday could see the return of some showers, going into Saturday morning. However, Sunday is expected to be mainly sunny.