The met office issued a yellow alert on Monday afternoon warning that rain and local thunderstorms are expected to affect the area from late on Monday night.
It said that the total rain accumulation is likely to locally exceed 55 millimetres in 24 hours.
The alert is in force from 10 pm on Monday night to 10 pm on Tuesday night.
This is the second alert issued by the met office today. Before noon, it issued a coastal waters alert, warning of strong to near gale winds and very rough seas after midnight tonight.
According to the latest weather forecast tonight will be mainly cloudy with scattered showers in most areas and isolated thunderstorms and snowfall in the mountains. Temperatures will fall to 7 C inland, 11 C on the coasts and 1 C in the higher mountains. Winds will be strong and the sea rough.
Tuesday will be mainly cloudy with rain in most areas, isolated thunderstorms and snow in the mountains. Winds will be very strong and the sea rough. temperatures will be 15 C inland and on the coasts and 4 C in the mountains.
Tomorrow night will be mainly cloudy with rain in most areas, isolated thunderstorms and snow in the mountains. Winds will be very strong and the sea rough.
Wednesday will be cloudy at intervals with scattered rain and isolated thunderstorms. Snow is expected in the mountains and semi-mountainous areas. The weather will gradually improve from late in the afternoon. Temperatures will drop to below average for the time of year.
Thursday will be mainly fine with temperatures close to average for the time of year. Friday will also be mainly fine with increased local cloud as from the afternoon. Temperatures will edge up to average for the time of year.