Met Éireann are maintaining their status orange fog warning for Ireland throughout tonight until 2pm Friday.
The national meteorological service say there will be very poor visibility, with fog lingering in many midland area, which will become more extensive and dense this evening and for a time tonight.
Visibility less than 100m in places. Motorists are being asked to use their fog lights where necessary.
This dense for will be accommpanied by some frost with lows overnight falling to -2.
Friday is forecast to be rather windy, with strong and gusty southeasterly winds. It will be mainly dry at first with a few bright spells in eastern areas, but rather cloudy overall, with patches of drizzle and mist scattered about.
In the afternoon, a spell of heavy rain will move in from the Atlantic, affecting much of Munster and Connacht by nightfall. Afternoon temperatures will range from 5 to 9 degrees Celsius, coldest in the north.
Friday night will be windy and very wet over the western half of the country, with heavy possibly thundery rain in many areas and some flooding. Winds will be strong to gale force and gusty southeasterly. Windy and mostly cloudy elsewhere too, with the rain spreading eastwards all the while and with some heavy rain in places by dawn. Lowest temperatures 4 to 8 C.
Further rain in all areas during Saturday, with some heavy falls in more eastern areas. A misty, mostly cloudy day and a breezy start too, but the stiff southeast winds will moderate gradually. Top temperatures 7 to 10 C. The rain will peter out after dark and it will become misty. Some patches of fog will form and also some frost. Lows of zero to plus 3 C., are expected, in slack variable breezes, coldest in western areas.
Sunday will be a mainly dry day, with just scattered patches of mist and drizzle. Overnight fog and any frost should clear. Top temperatures 7 to 10 C. At this stage, it looks as if Sunday night will turn wet and breezy.
Early days of next week: Cool, windy and showery, with some wintry showers in places. Winds fresh to strong westerly much of the time. Cold at night, with some frost in places.