Snow has hit Londonderry and the west of Ireland, as a yellow weather warning is issued by the Met Office.
Showers turned to snowfall in the north-west on Tuesday, where residents shared photographs online of parks and streets blanketed in the white stuff.
The Met Office has warned of the risk of some travel disruption and difficult driving conditions, as snow showers are set to continue through Tuesday night into Wednesday morning.
Forecasters say 10cm or more of snow is possible on high ground. On low ground, lying snow will tend to melt between showers by day but 1-3cm may settle on Tuesday night.
Icy stretches will also form in the evening, lasting well into Wednesday morning in the north.
Gritters will be out salting at-risk roads on Tuesday afternoon and evening but drivers have been urged to exercise caution.
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The Met Office chief forecaster said: "Following the eastwards clearance of the frontal system on Tuesday, a cold and unstable westerly airstream is expected to follow across many parts of the UK which will persist through Tuesday night into early Wednesday."
A dry, frosty night lies ahead for the rest of Northern Ireland, with temperatures predicted to drop to -2 °C in Armagh and Fermanagh.
More snow may fall on Friday and Saturday this week.
NI Water has warned customers to prepare for frozen pipes by checking where their stop valve is and keeping the contact number of a registered plumber on hand to deal with any bursts.