Long Range Weather Forecast For Ireland (20 December 2020)

TRENDS for the week of 20 to 26 Dec 2020

-- Temperatures will average 1 to 2 deg below normal.
-- Rainfall will average 50 per cent of normal values, possibly as low as 25 per cent in the north.
-- Sunshine will average 25 to 50 per cent above normal, although some days will be overcast.


TODAY will bring a mixture of cloud and brighter intervals with passing showers, mostly confined to west and north. Highs 7 to 9 C.

TONIGHT will become wet in the south and central counties, with rain becoming steadier towards morning, and temperatures will only fall a little in the evening before becoming steady 5 to 7 C.

MONDAY the rain (10 to 15 mm totals expected) will gradually push east with a moderate southwest to west wind turning more northwesterly, with partial clearing. Highs 8 to 10 C.

TUESDAY will be rather cold, bright across Ulster, north Connacht and north Leinster, and mostly dry there also, highs 3 to 6 C. Further south it will be overcast and some light rain is possible, with sleet or wet snow on hills. Highs 4 to 7 C in those areas. Light easterly winds will develop.

WEDNESDAY there is some risk of snow or sleet in the morning across parts of Munster and south Leinster, likely to be melting on contact except on higher terrain. Further north, although mainly dry, some streamers could develop from the Irish Sea as well as the North Atlantic, bringing some parts of Leinster and north Connacht mixed wintry showers. Winds increasing to northeast 40 to 70 km/hr, lows 1 to 3 C and highs only 3 to 5 C.

THURSDAY 24th will be a cold, bright day with northeast winds turning more northerly, which may keep any Irish Sea wintry showers off or near the Wicklow coast. Dry in many other areas but there could be mixed wintry showers in west Ulster and north Connacht also, in northerly winds 40 to 60 km/hr. Lows near -1 C and highs near 5 C.

FRIDAY (Christmas Day) will have a frosty start and some icy road conditions are possible, inland east and south in particular will be quite cold with morning lows -2 to -5 C. Thick frost is possible for some areas although rising temperatures after midnight in the west may remove that frost before Christmas morning. Some hazy sunshine later through increasing high cloud, then becoming quite breezy (westerly 40 to 70 km/hr) by afternoon and evening, highest temperatures will range from 9 C in coastal south and west, to 5 C in east Ulster and north Leinster. Windy with occasional light rain or drizzle by the night of 25th-26th, temperatures may peak around 9 or 10 C at some early morning hours then a slow drop in temperatures will set in, winds quite strong at times may reach west-northwest 70 to 110 km/hr.

SATURDAY (26th) will remain windy, any milder turn (which some guidance shows briefly) will end with passage of a cold front, but some guidance already indicates the whole day will be quite cold as winds become northwest then north 50 to 80 km/hr. Morning lows 3 to 5 C then afternoon temperatures similar or falling slowly.

SUNDAY (27th) to MONDAY (29th) is looking quite cold with the risk of localized snowfalls, whether of streamer origins, or small low pressure areas rotating around a larger low in Belgium and northeast France. These lows could contain mixed wintry forms of precipitation near sea level and snow for hills, as temperatures will be struggling to get much above 4 C anywhere (and could be colder than that for parts of these days).

The further outlook is quite uncertain at this point, this colder air will try to hang around for several more days but the Atlantic resumes its active storm track too, so a clash is possible, guidance is mixed as to where the rain-snow boundary will set up, but it could be at least through some parts of Ireland, possibly dividing the country into somewhat milder and continued cold zones at times.

There is plenty of potential for occasional light snowfalls in all of this, but nothing that yet shows a high probability of being disruptive on a larger scale. Watching it all carefully of course.

- Peter O'Donnell for IWO