Major thunderstorms battered parts of southern Ontario on Tuesday afternoon, triggering numerous flight delays at Toronto's Pearson International Airport.

Crowds of passengers at Toronto's Pearson International Airport wait for their luggage on Tuesaday after lightning warnings prompted ground crews to suspend services. (CBC)The severe weather, which is expected to extend into the evening, forced ground workers at Pearson to suspend ground operations for more than an hour over the threat of lightning strikes.

Around 4:30 p.m. ET, large crowds of travellers gathered inside Pearson's Terminal 1 as flight boards showed "delayed" notices for more than half of incoming and departing flights.

The CBC's Cheryl Krawchuk, who was on board a flight arriving from Halifax, reported that her plane was waiting on the tarmac for more than an hour before it was allowed to arrive at the terminal and let passengers disembark. She said the pilot of her flight told passengers that about 50 planes were grounded at the time.

Scott Armstrong, spokesman for the Greater Toronto Airports Authority, would not confirm how many flights were delayed.

"The thunderstorms have caused some delays, but overall, things are running smoothly, given the weather," he told CBC News.

Airports in Ottawa and Montreal were also being affected by the storms, he said.

At the height of the afternoon storms, torrential rainfall created headaches for drivers by reducing visibility to almost zero on some GTA roads.

Tornado warnings issued earlier in the day were lifted, although Environment Canada's Geoff Coulson said that could change.

Coulson said the system, being caused by a cold front, could bring heavy rain, hail, lightning and winds in excess of 100 kilometres per hour.

The storms in the Toronto area are expected to continue into the evening, but finish by midnight.

With files from Cheryl Krawchuk and The Canadian Press