Spain has begun its first heatwave of the summer with more than a dozen regions gripped by temperatures in excess of 41 degrees Celcius (106 Fahrenheit), the country's meteorological institute said Monday.

Clear skies and very dry air are set to allow temperatures to soar across much of the penninsula until at least Thursday, said Angel Alcazar, the agency's spokesman.

The southern cities of Andujar, Montoro and Merida began to hit 42 degrees on Sunday and the valleys of the Tagus, Guadiana and Guadalquivir rivers would also experience "significantly high" temperatures, Alcazar said.

He said that six of the 13 regions currently affected by high temperautures would be on "orange alert," just below Spain's maximum hot weather "red alert" warning level.

Spain's state weather agency Aemet recorded a high of 44.5 degrees Celsius at Zaragoza airport in July last year, the highest temperture noted since record-keeping began 30 years ago.