what will the weather be like over Christmas?

There will be snow on the 24th December

Enjoy.

We'll see. But my prediction is snow on christmas eve evening.

The warm front from the south will confront a cold north easterly in dundalk and across the west creating precipitation and will slowly move south on Christmas eve. I kid you not.

The postman has spoken and he said snow

GFS goes for a mild and settled Christmas day. ECM, on the other hand, has misery written all over it with a strong W flow with squally hail and sleet showers. Still very uncertain.

The last thing we want is bad wind at Christmas. It was bad enough in Cork, Mayo and Donegal today for sure and I know as I am in the former! Of course, hurricanes and other poor weather ruined other recent Christmases before:

1997: extreme 100+ mph (I mean mph not kph!!) with gusts reaching 120+ mph in some places put out the power for between 3 to 7 days for people in Southern half of Ireland from Christmas Eve on, but the storm's ferocity was felt as far north as Leitrim and Cavan too.
1998: Unfortunately, the same happened again this year. A mirror image storm/hurricane came along but this time it was on St Stephen's Day. The Northern half of the country bore the brunt but it was again a nasty piece of work everywhere and again power outages of between 3 and 7 days were common.
1999: Another bad storm comes in Christmas 1999 and again puts out the power. It is less severe than the previous 2 though but is followed up with extremely cold weather.
December 2009/January 2010: The lead up to Christmas this year was remarkably cold for the time of year and snow showers and ice made roads treacherous on occasion. However, the cold spell of December/January 09/10 did not inconvenience one too much.
2010: The most recent worst weather event came on 27 November 2010 with snowfalls that made all roads even main roads treacherous within hours. 2 things made this one VERY different to past snow events: it came early and it lasted until St Stephen's day. A whole month. Many until then dreamed of a white Christmas (and snow on Christmas eve/day when all the shopping is done would be fine) but the reality of pre-Christmas snow made shopping and attending events extremely difficult if not impossible for many. The novelty of snow also faded due to its lengthy stay (even so much so, it overshadowed the IMF/EU troika coming into Ireland and the budget as the biggest worry for people).

Most other Christmases were generally either mild and sunny (very common believe it or not: last year is an example), mild and wet, cold and sunny/frosty, or cold and wet. This year we will have to wait and see: everything from horrid wind to bad snow as usual have been mentioned (and are possible of course as we have seen) but hopefully we will be pleasantly surprised.