Weak high pressure is affecting the area, with a hot air mass forecast for Monday bringing higher temperatures, the met office said in its early morning weather bulletin on Sunday.
Sunday will be mainly fine with intervals of increased mainly fine cloud. Temperatures will be 31 C inland, around 28 C on the south and east coasts, around 26 C on the west and north coasts and 25 C in the mountains.
Tonight will be mainly fine with intervals of increased high cloud. Light fog and low cloud are forecast in the early hours of the morning. Temperatures will fall to 16 C inland and on the west and north coasts, around 18 C on the remaining coasts and 15 C in the mountains.
Monday, Tuesday and Wednesday will be mainly fine with increased higher cloud at intervals. There may be light dust in the atmosphere on Wednesday, mainly from the afternoon on.
Temperatures will rise on Monday to above average for the time of year, with a further noticeable increase forecast for Tuesday and Wednesday.