The service's forecast for Friday to Sunday says: "From Friday into the weekend it will be remaining rather cloudy with patchy rain and hill snow at times.
Its long-term forecast for Sunday to Tuesday, February 25, says: "There is a chance of even colder conditions developing temporarily, which would see more wintry showers, especially in northeastern areas.
The Met Office meanwhile has warned cold easterly breezes will bring chilly temperature to parts, saying it could get "even colder" with the chance of wintry showers.
The transition between colder and milder conditions remains uncertain, but towards the end of this period, the milder, wetter conditions are likely to have spread across much of the country.
Minimum temperature maps show the mercury could drop to 0C or lower everywhere apart from in the far south-west, parts of Wales and Northern Ireland - meaning only three areas will be spared.
