The met office has issued another yellow alert — the third in as many days — warning that maximum temperatures are expected to rise to around 41 C inland and around 33 C over the highest mountainous areas.
The warning is in force from 11 am to 5 pm.
In its afternoon weather forecast, the met office said seasonal low pressure and a warm air mass are affecting the area.
Tomorrow will be mainly fine with temperatures of 41 C inland, 32 C on the west coast, around 35 C on the remaining coasts and 33 C in the mountains.
Monday night will be mainly fine with possible low cloud and patchy fog at dawn.
Tuesday will be mainly fine while on Wednesday and Thursday there will be intervals of increased cloud.
Temperatures will remain at the same levels on Tuesday, edging down on Wednesday and Thursday but remaining at above average for the time of year.