The met office has issued a yellow alert for Wednesday saying temperatures will reach 40 C inland. It added that minimum temperatures will be around 26 C inland and over the south and east coasts.
The extreme high temperature warning is in force from 12 noon through to 6.00 am on Thursday.
“Be aware that high temperatures are expected. Some health risks amongst vulnerable people e.g. the elderly and very young are possible,” it said.
In its weather forecast, the met office said Wednesday will be mainly sunny with increased clouds in the mountains with the possibility of isolated showers or storms.
Temperatures will rise to 40 C inland, 32 C on the west coast, around 35 C on the remaining coasts and 29 C in the mountains.
Localised fog is possible early on Thursday morning.
The hot temperatures will continue through to Friday before easing off on Saturday
Temperatures will be 40 C inland on Thursday, 33 C on the west coast, 35 C on the remaining coasts and 30 C in the mountains. They will remain at the same levels on Friday before edging down to the average for the time of year on Saturday.