Inland temperatures on Thursday are expected to peak at 40C, with a yellow warning in place from 12 noon till 16.30pm.
Yellow warnings are issued for temperatures that may affect vulnerable people, especially the elderly and very young.
The Meteorological Department said the weather on Thursday would be mainly clear, with clouds over the mountains in the afternoon.
Temperatures will reach 40C inland, 32-34 along the coast and 29 in the highest mountains.
Overnight, temperatures will drop to 21 inland, 22 along the coast and 19 in the mountains.
Isolated showers are expected on Friday in the mountains and possibly inland.
Temperatures on Friday are not expected to change but will drop over the weekend.
Click here to change your cookie preferences