Mexicans basking in temperatures of 31C (87.8F) just hours before were quickly cooled down when a strong hailstorm fell in Guadalajara, covering streets in layers of ice up to two metres deep.
The freak storm in the early hours of Sunday shocked residents and left vehicles trapped in the deluge of ice.
The hail fell after temperatures suddenly dropped from 22C (71.6F) to 14C (57.2F).
Two people caught in the hail even showed early signs of hypothermia.
"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 phenomena," he said.
Guadalajara, located north of Mexico City and with a population of around five million, has been experiencing summer temperatures of more than 30C in recent days.
While seasonal hailstorms 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.
No casualties were reported.
- What is hail?
Despite it being summer in Mexico, and with daytime temperatures into the 30Cs, hailstorms are not that rare.
While the temperature on the ground is warm, high up it can still easily fall below freezing, allowing ice to form.
Hailstorms form when warm, moist air from the surface rises upwards forming showers and storms.
Temperatures higher up, even in summer, can get well below 0C and so ice crystals form along with something called "supercooled water" which then grows into pellets of ice.
Hail stones form in cumulonimbus (the fluffy-looking ones) clouds in thunderstorms.
Air pressures in the clouds cause the hailstones to rise and fall within them, gaining ice layers each time they go up to the top where temperatures are less than -20C.
Eventually they become too heavy and gravity causes them to fall to the ground.
Electrical activity in these clouds often leads to lightning.
Thunder is the sound which accompanies lightning due the increasing temperature and pressure of the air.
- But why did so much fall in Guadalajara?
Warm air can retain more moisture, so the warm weather in Guadalajara, combined with low air pressure high up, pulled lots of moisture up, creating the hailstones, Alex Deakin from the Met Office.
He added that a slow-moving thunderstorm meant the clouds from which the hail fell, stalled over Guadalajara, meaning the hail - eventually building up to two metres - continually fell in the same place.
Mountains in the region helped contribute to this "back building", Mr Deakin said.
- Are events like this rare?
Yes, but since the hail only fell on Sunday, we do not know quite how rare it is.
A similar event in the Devon town of Ottery St Mary in 2008, when around one metre of hail fail, was described as a one in 200 years event, Mr Deakin said.