The Road Safety Authority says a combination of oil, dirt and rubber on dry roads can be 'treacherous' when rain falls for the first time after a dry spell.
Spokesperson Brian Farrell says motorists can stop their journeys in bad conditions:
"If you have a particularly heavy downpour and visibility is reduced, if you feel that it is safer, or if you feel more comfortable as a driver pulling in and waiting for it to pass, absolutely always do what you consider to be the right thing to do. The only thing I would say is just make sure that if you are pulling in, that it's clear, that you're not going to cross over into the path, or put a pedestrian or vulnerable road users cyclists at risk."