Emergency services in Valls, in the Tarragona region, were alerted in the early afternoon but were unable to resuscitate the child, a police spokesperson told AFP.

"Everything seems to indicate that it was negligence on the father's part. The child spent the entire morning in a locked car under the sun," they added.

"It was heatstroke. Even an adult would have died."

Temperatures in Valls reached up to 32 degrees Celsius (89.6 degrees Fahrenheit) in the shade on Tuesday morning, according to the national meteorological agency Aemet.

Spain has been hit for several days by intense heat that has spread across the Iberian peninsula to France, Italy, the Balkans and Greece, triggering health warnings and alerts over the risk of forest fires.

Several areas of the country have seen the thermometer rise to well above 40C and record highs for the month of June.

Aemet said earlier on Tuesday that Spain had had its hottest June on record, with an average temperature of 23.6C -- beating the previous high of 22.8C set in 2017.

On Saturday, two road workers died of suspected heatstroke in Cordoba, in the south, and Barcelona, in the northeast.

In Portugal, the country recorded its highest-ever single-day temperature in June -- 46.4C -- on Sunday in Mora, some 100 kilometres (60 miles) east of the capital, Lisbon.

The previous June high was 44.9C in the southwestern town of Alcacer do Sal in 2017, the IMPA weather agency said.

Some 37 percent of IPMA monitoring stations recorded temperatures higher than 40C on Sunday, it added.

A number of regions, including around the capital, were put on red alert on Sunday and Monday.

Eight Portuguese inland regions remained on the second-highest alert with the highest risk of forest fires, especially woodland areas in the centre and north of the country.

Human-induced climate change is being blamed for stoking hotter and more intense heatwaves, particularly in cities, where tightly packed buildings amplify temperatures.

Michael Byrne, a reader in climate science at the University of St Andrews in Scotland, said heat domes -- when warm air is trapped in the atmosphere -- were nothing new.

"What is new are the temperatures heat domes deliver. Europe is more than two degrees Celsius warmer than in pre-industrial times, so when a heat dome occurs it drives a hotter heatwave," he added.

"Climate change is loading the dice such that when a heat dome does occur, it brings hotter and more dangerous temperatures," he added.

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