Met Éireann says patches of mist and fog will develop tonight, so drivers may meet reduced visibility even if the road is clear when they leave. The forecast does not identify individual roads or say how dense or long-lasting any patch will be. Plan for changing conditions and judge each stretch by what is visible.

Understanding Patchy Fog

Patchy conditions do not mean that every route will be affected. A national forecast cannot describe conditions road by road, and visibility may differ between separate parts of the same journey. Clear conditions at departure should not be taken as confirmation that the entire route will remain clear.

Keep reassessing the road ahead, mirrors and roadside detail. If lane markings, junctions or other vehicles become harder to see, adjust early rather than waiting until the view is severely restricted. Avoid using the speed or lights of another vehicle as the sole guide to what lies ahead.

Before Setting Off

Prepare the car while stationary so fewer adjustments are needed on the move. Windows, mirrors, lights and ventilation should be ready before entering any mist or fog.

  • Clear condensation from the windscreen, side windows and mirrors.
  • Use dipped headlights and check that the car’s lights are operating.
  • Do not rely entirely on automatic light settings.
  • Set the ventilation to help keep the glass clear.
  • Have the wipers ready and keep essential controls within easy reach.

Driving Through A Patch

If the visible distance shortens, reduce speed smoothly and increase the space to traffic ahead. Travel at a pace that allows you to stop within the road you can see. Avoid following rear lights too closely, as that can draw attention away from the immediate road surface, junctions and roadside hazards.

Delay overtaking when the visible stretch is limited. Look carefully for pedestrians, cyclists, animals and vehicles entering from side roads. Sudden braking or sharp steering should be avoided where a gradual response is available, particularly when other drivers may also have a restricted view.

The wider forecast also mentions persistent and occasionally heavy rain in parts of the country on Monday afternoon and evening, followed by showers spreading to all areas on Wednesday, some heavy or prolonged. That does not establish that tonight’s fog will persist or coincide with rain, so treat each forecast period separately.

Check the latest national forecast before departure, then respond to the conditions actually ahead. Slow progressively, leave more space and keep every window clear throughout the journey.