Low pressure is affecting the area and there will be dust in the atmosphere until Tuesday afternoon, the met office said. Concentrations are expected to be higher on Sunday.
Today will be partly cloudy and at intervals cloudy with scattered light showers possible in the morning.
Isolated rain and possible thunderstorms are forecast at midday and in the afternoon in the mountains and inland.
Temperatures will be 22 C inland and on the west coast, around 20 C on the remaining coasts and 14 C in the mountains.
Tonight will be mainly fine. Temperatures will drop to 9 C inland, around 11 C on the coasts and 6 C in the mountains.
Monday will be mainly fine but clouds that form at noon and in the afternoon may lead to isolated showers mainly in the mountains. Temperatures will edge up, mainly inland, to close to average for the time of year.
On Tuesday and Wednesday, there will be intervals of mainly fine weather and intervals of cloud. Scattered showers are forecast, mainly at midday and in the afternoon.
On Wednesday, thunderstorms are possible.
Temperatures will remain effectively unchanged on Tuesday at close to average for the time of year but will drop to below average on Wednesday.