An unprecedented record-breaking storm wreaked havoc in Spain on Saturday as it shut down the Valencia airport, left thousands without power and caused significant flooding, killing one minor.

The worst-hit area so far is the region of Valencia, where some towns have begun to resemble Venice after torrential rainfall.

The weather station at the Valencia airport recorded 66.1 liters of rain per square meter in just one hour – the most intense rainfall on record for November and the third-most torrential in recorded history, according to Spanish meteorological agency AEMET.

The torrential rain is accompanied by strong winds, hail and lightning.

At first, flights to the Valencia airport were being deferred because of flooding, but Spain’s airport service later announced that its runway has become "inoperative" due to a lightning strike.

On Friday night, a 17-year-old boy was killed in the province of Zaragoza when a tree he was taking shelter beneath fell on top of him.

In Tarragona, Catalonia, the storm has left around 6,600 residents without power.

Flooding has also been reported in more central areas of Spain such as Avila.

This is yet another record-breaking weather event in Spain this year, which saw the hottest summer and hottest October on record.

According to AEMET, since record-keeping began in 1959, the Balearic Sea has never been this warm at this time of year.

The warm water may help explain the unseasonable strength of this weekend’s storm.

"A warm sea does not necessarily mean torrential rains, but if the right atmospheric conditions are in place, a warm sea means more available energy and more power for convection and storms," tweeted AEMET.

The agency said climate change is behind warming temperatures on land and at sea.

"Although it's hard to attribute individual phenomena to climate change, what’s true is that the Mediterranean area is already noticing an increase in torrential rainfall," it added.