With freezing temperatures now expected on Wednesday and Thursday, large-scale strikes are expected to disrupt public services.
Forecasters warned that frequent snowfall was possible and “could cause further travel disruption Wednesday into Thursday.” Counties Antrim, Londonderry and Tyrone will be affected.
There are fears the strike could lead to Northern Ireland’s roads being unpaved.
A previous yellow warning for showers, which were gradually increasing as snow, has been extended from 3am on Monday to 9am on Tuesday.
The Met Office said on Sunday: “Strong northerly winds will bring showers across inland Northern Ireland on Monday, initially as snow in the highlands and then as sleet and rain in other areas.”
“However, as increasingly colder air spreads southward, showers will fall as snow at all levels by late morning.
“Up to five centimeters of snow could accumulate on high-altitude routes such as the Coleraine Pass and the Glenshane Pass.
“A few centimeters of rain is expected at low levels, with more frequent showers expected in northern counties. Ice will pose an additional risk to all areas into the evening.”
The Met Office has also issued a heavy snow warning for Northern Ireland for 48 hours from midnight Wednesday to midnight Friday.
“The heaviest and most frequent snowfall will occur across northern Scotland on Wednesday morning, with development later in the day in parts of south-west Scotland, Northern Ireland, north-west England and Wales.” the paper said.
“Snow showers could continue Wednesday night into Thursday.
“Snowfall amounts will vary depending on the nature of the showers, but 2-5cm of snow is expected in many locations. In areas where showers are more systematic, some low-lying areas could receive up to 10cm of snow in a few hours. There is a gender.
“More than 20 centimeters of snow could accumulate in some places in the north of Scotland.”
The Department for Infrastructure (DfI) did not give a final answer when asked last week whether road resurfacing works would be operational, saying that its responsibility would cause “widespread disruption” to public services, but that “in an emergency Countermeasures will be taken,” he said. This is to reduce potential impacts and provide limited essential services such as polishing. ”
However, a labor union official declared, “There will be no gnashing of teeth.”
It is understood that there are some private gritters in Stormont that provide cover, but at best they will be able to handle motorways, dual carriageways and some of the busiest roads.
Snow is also expected to fall in parts of northern Scotland on Sunday as cold air from the Arctic brings in cold air.
A yellow weather warning for snow and ice is in place throughout the day from Sunday to Monday for areas including the Highlands, Orkney and Shetland Islands.
The Met Office has warned that around 10cm of snow could fall in parts of northern Scotland over the next two days.
Forecasters expect the snow to move southwards this week, potentially bringing wintry weather to parts of northern England on Tuesday.
Areas in the south of England are said to be at “low risk” of snowfall.