The met office issued a yellow alert warning of heavy rain and possible hailstorms as a low pressure system affects the area.
The total rain accumulation is likely to locally exceed 35 millimeters in 24 hours. The yellow alert is in force until 10 pm on Wednesday.
Local showers and isolated thunderstorms are expected at intervals on Wednesday, with snow or sleet in the mountains. Rain may be heavy in places, the met office said. Temperatures will be 15 C inland, 15 C on the coast and 6 C in the mountains.
On Thursday and Friday the weather will be cloudy at intervals with scattered showers and/or thunderstorms and sleet in the mountains.
Temperatures will edge up to higher than average for the time of year.
Temperatures will drop again on Saturday with scattered showers and/or storms expected and snow in the mountains.