Officials reported 1,149 excess deaths in Spain from August 3-18 that could be attributed to the scorching temperatures, the public health agency said.

The institute used data from Spain's Mortality Monitoring System (MoMo) that was compared to historical trends.

It also incorporates external factors, such as weather data from the national meteorological agency AEMET, to assess likely causes of mortality spikes.

Although MoMo cannot confirm a direct cause between deaths and high temperatures, it provides the most reliable estimate of fatalities in which heat was likely a decisive factor.

For July, the Carlos III institute had attributed 1,060 excess deaths to intense heat, a 57 percent increase over the same period last year.

Climate experts say global warming is driving longer, more intense, and more frequent heat waves around the world.