A freak hail storm has struck Guadalajara, one of Mexico's most populous cities, shocking residents and trapping vehicles in a deluge of ice pellets up to two metres deep.

"I've never seen such scenes in Guadalajara," said the state governor, Enrique Alfaro.

"Then we ask ourselves if climate change is real. These are never-before-seen natural phenomenons," he said. "It's incredible."

Guadalajara, located north of Mexico City and with a population of around five million, has been experiencing summer temperatures of around 31C in recent days.

While seasonal hail storms do occur, there is no record of anything so heavy.

At least six neighborhoods in the city outskirts woke up to ice pellets up to two metres deep.

While children scampered around and hurled iceballs at each other, Civil Protection personnel and soldiers brought out heavy machinery to clear the roads.

Nearly 200 homes and businesses reported hail damage, and at least 50 vehicles were swept away by the deluge of ice in hilly areas, some buried under piles of pellets.

While no casualties were reported, but two people showed "early signs of hypothermia," the state Civil Protection office said.