Thursday will be mainly fine with increased high cloud at intervals as weak high pressure continues to affect the area, the met office says.
Temperatures will rise to 25 C inland, around 23 C on the coast and 16 C in the mountains.
Tonight there will be intervals of increased high cloud. Temperatures will fall to 9 C inland, around 11 C on the coast and 5 C in the mountains.
On Friday, Saturday and Sunday there will be intervals of increased cloud. Isolated, mainly light showers, are possible.
Temperatures will edge down gradually over the next three days to close to average for the time of year.