A Hamilton school superintendent defended several rowing coaches on Thursday, after nine students suffered mild cases of hypothermia when their boats capsized during a sudden storm.

Krys Croxall, superintendent of student achievement for the Hamilton Wentworth District School, said the coaches of a local rowing club had read weather warnings suggesting the region would be hit by severe windstorms later in the day.

Instead, fierce, damaging winds swept across southern Ontario as early as 7 a.m. on Thursday, flipping cars and small airplanes, knocking down hydro lines and capsizing boats in Lake Ontario, including two row boats piloted by the student athletes.

Hamilton police were forced to deploy marine units to rescue 13 students from Hamilton's Westdale High School, after the boats capsized in the Hamilton Harbour. Nine students were taken to hospital suffering from mild cases of hypothermia.

Croxall said the chaperones had no reason to anticipate the sudden storm would hit while the group of some 100 students was on the lake.

"The water was smooth and calm with no waves or white caps," Croxall told ctvtoronto.ca. "Usually if there's any question the coaches from the five schools meet and make a decision, but this morning there was no question because it was so calm. It wasn't until 7 a.m. that the weather just blew-up."

Croxall added that when the storm hit, causing two-metre high waves, most of the rowers were on their way back into the boating club.

However a boat of four students, a boat of nine students and a coach's boat, holding all the life jackets, were farther away on the North Shore course. The students' boats capsized, throwing them into the frigid water.

It was at that point the coaching boat handed out lifejackets and then picked up four of the students, taking them back to the boating club.

The coach had planned to return to pick the boys up but police arrived and collected the nine remaining teens after they had spent about 20 minutes in the water, Croxall said.

Croxall said that they would review their safety measures, but said she was confident the coaches had acted appropriately.

Croxall said all rowers are currently required to pass a swimming test before being allowed to join the rowing team. She added that only two of the boys remained in hospital Thursday afternoon.

Renee Common, one of the rowers, said there was one rower who couldn't swim.

"He was fine, but it was scary," she told CTV Toronto's John Musselman.

Hamilton Police Supt. Bill Stewart said they were lucky to have volunteers from the boating club at hand during the incident, which saw wind gusts reach 90 kilometres per hour.

"We were fortunate to have a marina close by," he said. "They were able to rescue some of the students from the water."