The Met Office says a weather warning for snow and ice across Northern Ireland is now in place until midday on Wednesday.
It comes after sub-zero temperatures gripped the region overnight into Tuesday, leading to difficult travel conditions and school closures.
The north west has been particularly badly hit.
Credit: Cop/Vosa Watch NI and Marine Hotel Ballycastle
Police in Derry said they dealt with 19 crashes in the city as well as city, Strabane, Slaughtmanus and Donemana.
Meanwhile Derry City and Strabane Council has advised residents that services including bin collections could also face disruption.
The cold snap is expected to continue, with a yellow-level Met Office warning remaining in effect across the region.
"Snow showers will affect these areas through Tuesday afternoon and continue in many places overnight, and into Wednesday morning," said the Met Office.
"Accumulations of a couple of centimetres are likely at low levels, with higher ground anywhere is the region potentially seeing 5 to 10cm, and up to 15cm for the higher ground in northern Northern Ireland, and mid-northern Wales.
"In addition, icy stretches are likely to form following showers."
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