The warning comes after a treacherous morning on the roads in Northern Ireland on Monday.Police said they dealt with 42 incidents between 6am and 9am across the region.The NI Ambulance Service (NIAS) reported attending the scene of 15 road traffic collisions, one of which was fatal, during the same time period.NIAS spokesman John McPoland told UTV: "Our crews dealt with incidents in Derry, Belfast, Craigavon, Lurgan, Armagh, Killyleagh and Downpatrick - they were everywhere."It was an exceptional three hours for us. Normally, in the space of a day, we would expect to deal with maybe 12 or 13 road traffic collisions, so this was a big morning for us."Both the police and the ambulance service said that the incidents could not be specifically linked directly to the cold weather conditions.However, black ice is thought to have played a part in the morning's disruption.During the morning, police urged motorists to exercise caution on roads which were said to be "extremely treacherous" in places.The Lurgan and Craigavon areas were reported to be among the worst affected, but black ice was also reported in Armagh, Portadown and Newry.NIAS attended 15 RTC's between 6 and 9 this morning incl one fatal. Drivers should be careful, pay attention, wear seatbelt and don't speed— NIAS (@NI_Amb_Service) January 13, 2014Police reminded motorists that they should stay at a safe distance behind other vehicles and reduce their speed.According to a Roads Service spokesperson, there was no evidence of frost in the Southern Division at about 3am on Monday morning and temperatures were well above freezing."An un-forecast dip in temperatures occurred at around 5-6am in areas of Southern Division, which caused road temperatures to fall below freezing, resulting in the formation of frost and ice on some roads," the spokesperson continued."This was compounded by isolated showers which occurred across the area, falling on road surfaces which were close to freezing."On becoming aware of the change in road conditions, Roads Service carried out gritting operations in Southern Division from 7am onwards on the parts of the salted network which had been affected."The warning for further icy conditions will be in place from 5pm on Monday until 10am on Tuesday.According to the Met Office, road temperatures will fall below freezing overnight, allowing icy stretches to form on untreated surfaces.Some travel disruption will be likely and may affect Tuesday morning's rush hour traffic.