The met office has issued a yellow alert for Monday night, warning of thunderstorms, heavy rain and strong winds.
It said that accumulated precipitation may exceed 35 millimetres per hour and the wind gusts 70 kilometres per hour.
The yellow alert is in force from 11 pm on Monday night to 5 am on Tuesday morning.
Earlier today, the met office said that tonight will be cloudy with rain and isolated thunderstorms, beginning in the west and north and later affecting other areas.
In places, rain will be heavy and thunderstorms may be accompanied by hail. Snow or sleet is possible in the higher peaks early on Tuesday morning.
Tuesday will be partly cloudy and cloudy at intervals with isolated rain and thunderstorms which may be accompanied by hail. Sleet or snow is possible in the higher peaks.
On Wednesday and Thursday, there will be periods of fine weather and of increased cloud cover which could lead to isolated showers. There may be sleet or snow in the higher peaks and other mountain areas.
Temperatures will drop slightly on Tuesday to average for the time of year and edge down further on Wednesday and Thursday to below average.