A status yellow weather warning has been issued for Leinster and Munster, as the national forecaster warns dense fog could create “hazardous” driving conditions.
Met Éireann said the fog warning will come into effect from 8pm on Wednesday and will remain in place until noon on Thursday.
The warning states that fog or freezing fog will develop on Wednesday, “becoming dense in parts of Munster and Leinster overnight leading to impaired visibility and hazardous driving conditions”.
“On Thursday fog will be slow to lift and may linger locally beyond the warning period,” the Met Éireann warning added.
It will be cold on Wednesday night, with lowest temperatures of -1 to +3 degrees, with frost forming, particularly in the southern half of the country.
On Thursday, fog and low cloud may persist in parts of the south and southeast through much of the day.
Elsewhere, Thursday will be a mainly dry day with a mix of cloud and sunny spells, with the possibility of some patchy drizzle in the west and northwest.
Highest temperatures on Thursday will be between 5 and 9 degrees, or a little cooler where fog persists.
The weather is expected to continue to be settled and largely dry throughout the rest of the week, with persistent frost and fog at night.
Mist and fog are forecast to redevelop on Thursday night, becoming dense in some parts of the country.
While most places will be dry on Thursday night, a few patches of drizzle are possible in Atlantic coastal counties. Lowest overnight temperatures will be between -2 to +3 degrees, with some frost forming.
Areas of mist and fog will be slow to clear once again through Friday morning, and they could linger for much of the day in some eastern and northern parts of the country.
Outside of that, Friday will be another largely dry day with a mix of cloud and sunny breaks, and just the odd, mainly coastal, patch of drizzle.
The mist and fog are expected to return on Friday night, becoming dense in places. However, it will be a warmer night, with lowest temperatures of between 0 and 4 degrees.
On Saturday, the fog will clear quicker than it did in the previous mornings, leaving another mostly dry day for most. However, cloud will thicken from the west, with outbreaks of light rain and drizzle spreading eastwards across the country overnight.
Lowest temperatures on Saturday night will range from 0 to 5 degrees, with mist and fog patches developing.