Motorists are being warned to take extra care on the roads as dense fog spreads across the country.
An orange weather warning has been issued by Met Eireann, which said fog will develop in many places tonight and will clear slowly on Wednesday.
The Road Safety Authority warned the conditions will greatly reduce visibility and make driving conditions poor and dangerous, particularly on motorways.
“Our advice is to switch on dipped headlights and fog lamps, reduce your speed and keep a safe distance from the vehicle in front,” said Moyagh Murdock, RSA chief executive.
“If the fog closes in, reduce your speed further and take your time getting to your destination.
“Open your window a little so you can listen out for other road users, particularly at junctions. Vulnerable road users should avoid, cycling or walking in fog unless it is a necessity.”
All road users are advised to listen to weather forecasts and general advice about driving conditions.
The RSA warned a collision involving one vehicle can quickly involve many more, especially if motorists are driving too fast and too close to one another.
“The biggest risk is of a multiple-vehicle pile-up on roads with higher speeds such as motorways and dual carriageways,” it added.
“The RSA is also advising vulnerable road-users such as pedestrians, motorcyclists and cyclists to ensure they are clearly visible to other road-users by wearing high visibility clothing and using lights.”