Ulster temperatures plunge to -18C
Temperatures in Northern Ireland fell to their lowest on record with -18C recorded at Castlederg, County Tyrone.
And it will be “horrendously cold” this week according to meteorologists.
Hundreds of schools are again closed with more snow overnight.
And Belfast's two main airports are open but cancellations and delays are expected to continue. City of Derry Airport is closed until 1100 GMT.
Lindsay Dovey, a forecaster with Meteogroup, said it will feel very cold during the week ahead.
“Today is going to be another cold one. Northern Ireland doesn’t look too bad, weather-wise.
“There will be some isolated snow showers and sunny spells, but it will be horrendously cold.
“Tomorrow, there is a chance of rain showers along the east coast and elsewhere it should be dry with sunny spells,” she said.
“Wednesday looks a bit messy. An area of low pressure is over the central area of the UK at the moment, so it depends on its position by then. It could bring snow showers across Northern Ireland. After that, on Thursday and Friday, it looks dry but very cold.”
Netweather are reporting the chances of a white Christmas in Northern Ireland at 55%, but Ms Dovey said it was too early to call.
“The Christmas period is less cold from the west, but how much less is anyone’s guess. At this stage, whether we get a white Christmas is anyone’s guess.”
Last night, at least 75 schools across Northern Ireland were reported as being closed due to the poor weather, with Co Antrim the worse affected, with 40 closures.
Meanwhile, as the country reels from a fresh battering of wintry storms, bookmakers reported record bets on a white Christmas.
Hopeful punters staked over £110,000 in less than 48 hours on the possibility of snow falling on December 25, Ladbrokes said.
After a second successive day of record-breaking festive flutters, the odds continue to tumble across the UK for snow on Christmas Day.
David Williams, from Ladbrokes, said: “Nobody's going anywhere but punters are going wild with white Christmas bets. It started on Saturday when we saw a huge surge in bets and interest has continued to snowball.
“It's white outside but we're feeling a bit grey as the forecasters tell us to get ready for a massive pay out.
“As the temperatures plunge, punters are warming to the idea of a record-breaking payout on Christmas Day.”
Snow in London on Christmas Day is as short as 11/10 — the shortest price offered by Ladbrokes since the 1980s.