Thursday will be mainly fine, but increased cloud after midday may lead to isolated showers, mainly in the mountains, the met office said in its early morning forecast.
Temperatures will rise to 36C inland, around 33C on the east coast, 31C on the north coast, 30C on the remaining coasts and 27C in the mountains.
Thursday night will be mainly fine with temperatures falling to 22C inland and the south and east coasts, around 21C on the remaining coasts and 17C on the mountains.
Friday will be mainly fine, however clouds that develop after midday may lead to isolated showers mainly in the mountains.
The forecast for the weekend is similar with mainly fine weather and increased cloud in the afternoon, mainly in the mountains.
Temperatures will edge up over the next few days to above the seasonal average.