Temperatures are expected to reach 40 C in parts of Andalusia, Murcia, Valencia and Extremadura as well as across the central regions of Castile-La Mancha and Madrid.
Las t. min. también han sido altas en general. la noche ha sido "tropical" en muchos puntos del S y el E peninsular. pic.twitter.com/1beLIzZvWd— AEMET (@AEMET_Esp) September 5, 2016
The national weather agency Aemet, put 17 provinces on amber alert for high temperatures with only the very north of the country escaping what is expected to be the last heatwave of the summer.
The high temperatures are forecast to last until Thursday when storms will bring cooler temperatures.
The high temperatures raise the risk of forest fires and in Javea, south of Valencia, firefighters were struggling to bring blazes thought to be set deliberately, under control.