See our gallery of weather photos submitted by Herald readers.

Here's a second gallery of reader photos of the hailstorm.

Hail bigger than golf balls dropped over parts of Calgary late Sunday night during a severe thunderstorm.

Kyle Fougere, lead meteorologist with Environment Canada, said the thunder cell started in the Sundre area west of Red Deer moving southeast while picking up power.

It caught the northern part of Calgary, with reports of hail five centimetres wide, larger than the size of the golf ball.

“We expect a significant amount of damage from this storm,” he said.

Environment Canada heard reports of damaged siding, and expect to hear more in the morning once people can go and check their vehicles.

The storm also produced large amounts of rain and lightning.

Most of southern Alberta was under a severe weather watch or warning Sunday night.

Herald reader Chris Ollenberger, from northwest Tuxedo, said, "Sounded like gunfire hitting the building, and came down so fast!"

A passenger on an inbound flight at Calgary International Airport reported a delay Sunday evening. "I'm on a flight from Kamloops and have arrived @ YYC but still sitting in plane waiting for thunder cell to pass," Craig Ellingson said in an email to the Herald. "Was told by pilot no grounds crew working, thus no flights leaving."

bforbes@calgaryherald.com