A weather warning for snow and ice is in place for Northern Ireland until later on Tuesday morning.
Temperatures in many inland areas were about -3C to -4C at about 07:30 GMT with icy conditions on roads as a result. Gritting has taken place.
Snow has been reported in a number of areas, including Ballyclare, Ballywalter, Downpatrick and Donaghadee.
The Met Office has said 1cm to 2cm of snow could settle in a few places.
It said it was most likely over higher ground and towards the north coast but due to the random nature of showers most places will manage to avoid snow.
The weather warning remains in place until 10:00 GMT.
Cold Arctic air is pushing south across Ireland and the UK this week, bringing temperatures below average by day.
A chilly, northerly wind will make it feel colder, especially around the coast and in exposed areas.
Overnight temperatures in the coming nights are likely to fall to -5C or -6C in some rural spots.
In the Republic of Ireland, a severe warning for ice has also been issued.
The Irish weather service Met Éireann said it was expecting hazardous conditions due to freezing temperatures.
Its warning came into effect at 18:00 on Monday until 10:00 on Tuesday.
Second warning for later this week
The Met Office has also issued more severe weather warnings for potentially disruptive snow later this week.
A yellow-level snow warning comes into effect at 03:00 on Thursday and is valid until 18:00 on Friday.
The warning suggests that snow could develop widely across Northern Ireland as a potentially deep area of low pressure moves across the UK and Ireland.
The worst conditions at this stage are forecast for Thursday, but throughout the warning period between 5cm to 10cm of snow is possible at many locations, even at low levels and potentially more on higher ground in counties Antrim and Londonderry.
Source – BBC News
