Seasonal low pressure is affecting the area and Thursday will be mainly fine with increased local cloud in the mountains.
Temperatures will rise to 39 C inland, around 31 C on the west coasts and the mountains and around 34 C on the remaining coasts.
Tonight will be mainly fine with the possibility of low cloud and patchy fog.
Temperatures will fall to 22 C inland and on the south and east coasts, around 21 C on the remaining coasts and 17 C in the mountains.
Friday, Saturday and Sunday will be mainly fine. There will be increased cloud in the mountains on Friday afternoon. Low cloud and patchy fog is possible at night and early in the morning.
Temperatures will remain at the same levels on Friday, edging up on Saturday to a little above average for the time of year and remaining at those levels on Sunday.