Yesterday, Guadalajara's 30'C heatwave broke suddenly when, at 1:50AM, the nighttime temperature suddenly plunged from 22C to 14C, causing small, sub-1cm hailstones to form and fall in great profusion, carpeting parts of the city in an 1.5m-thick layer of ice.
Although there was some flooding and damage to at least 200 homes, no one has been reported injured by the freakish storm.
State governor Enrique Alfaro attributed the storm to climate change.
According to BBC Weather, the hail probably melted on contact due to the high temperatures forming a layer of water upon which more hail could land and float.
This combination of water and hail likely moved down slope, with obstacles such as buildings blocking the flow and allowing more ice to accumulate on top.
The actual hailstones were relatively small, less than 1cm in diameter, and nothing like the golf-ball sized hail seen at times in severe storms in the US.
Mexico hail: Ice 1.5m thick carpets Guadalajara [BBC]
(Thanks, Kathy Padilla!)
En varios puntos de la ciudad sucedió esto que nunca había visto: una capa de granizo de decenas de centímetros. pic.twitter.com/56ZTfaW2lE
— Enrique Alfaro (@EnriqueAlfaroR) June 30, 2019