Most of Spain was put on high alert Wednesday as temperatures rose above 45 degrees Celsius with swathes of western Europe hit by a second heat wave in a matter of weeks.
France and Portugal have also seen scorching temperatures this week, and forest fires have broken out in all three countries.
Spain's state meteorological agency Aemet said some regions were "suffocating", especially the worst affected Andalusia in the south, Extremadura in the southwest and Galicia in the northwest.
They were all placed on high alert, meaning residents were asked to be cautious and watch the weather forecast. Travel was not advised "unless strictly necessary".
Apart from the Canary islands, all other regions of Spain were placed on lower levels of alert because of the heat.
The highest temperature in Spain on Wednesday was recorded in the Andalusian city of Almonte where the mercury hit 45.6 degrees Celsius at 5:30 pm (1530 GMT).
Several other southern cities such as Seville and Cordoba experienced temperatures above 44 degrees Celsius.
The heatwave began last weekend and is expected to last until Sunday.
Forest fires have already burned at least 3,500 hectares (8,600 acres) in western Spain near the border with Portugal.
Authorities in Portugal said one person had died in wildfires, after a body was found in a burned area in the northern region of Aveiro.
In Spain, nearly 500 residents have been temporarily evacuated due to a fire northwest of Madrid, which firefighters battled to control on Wednesday, regional emergency services said.
Heatwaves have become more frequent due to climate change, scientists say. As global temperatures rise over time, they are expected to become more intense.
Spain has already suffered from drought this year, with water reserves down to 44 percent of capacity, compared to an average of 65 percent at the same period over the past 10 years.
The hottest temperature ever recorded in Spain was 47.4 Celsius last August.