A status orange national weather alert is in place as Met Éireann predicts dense fog will persist into the afternoon.
Widespread frost is expected clear, but the fog is likely to linger in central and eastern areas.
The warning is valid until noon.
DUBLIN: Heavy fog this morning on the M50 and in the City Centre. Drive with care. Use fog lights in affected areas. http://t.co/EY0qAeQ9mE
— AA Roadwatch (@aaroadwatch) November 26, 2014
AA Roadwatch reported low visibility in Dublin City Centre, Monaghan Town, Wexford Town, Tullamore, Carrick-on-Shannon, Mullingar, Roscommon, Navan and Drogheda.
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It also advised motorists to take extra care and use fog lights in affected areas.