Very mild, wet and stormy
December 2023 was dominated by Atlantic low pressure systems with four named storms affecting Ireland. An arctic air mass, with high pressure to the north and low pressure to the south, kept it relatively dry and cool for the first five days. Towards the end of the first week, Atlantic low pressure took control and brought mild, wet and very windy conditions up to the 11th. Storm Elin and storm Fergus, both named by Met Éireann, crossed directly over the country and brought widespread wet and windy weather on Saturday 9th and Sunday 10th. Low pressure stayed in control for the rest of the second week. During the third week low pressure moved further north as high pressure to the south became more influential. This brought some drier periods, especially over the South and East. It became windy again towards the end of the third week with blocking high pressure over the Atlantic and low pressure over Scandinavia squeezing the isobars together over Ireland. Further bands of rain or showers crossed the country with the bulk of the rain in the North and West. Christmas day was mild, damp and cloudy with weak weather fronts crossing the country in a westerly airflow. The final week saw low pressure moving closer to Ireland again. A complex area of low pressure, named storm Gerrit by the UK Met Office, brought several pulses of wet and windy weather on Wednesday 27th and Thursday 28th, including some thunderstorm activity. The month finished with storm Geraldine, named by Météo-France, bringing further wet and windy weather.
Rainfall: Above average in most places, highest in the West and Northwest
The majority of monthly rainfall totals were above their 1981-2010 Long-Term Average (LTA). Percentage of monthly rainfall values ranged from 89% (monthly rainfall total of 68.8 mm) at Phoenix Park, Co Dublin to 184% (monthly rainfall total of 214.2 mm) at Malin Head, Co Donegal. Monthly rainfall totals ranged from 68.5 mm (94% of its LTA) at Dublin Airport, Co Dublin to 293.8 mm (163% of its LTA) at Newport, Co Mayo. The highest daily rainfall total was 31.4 mm at Johnstown Castle, Co Wexford on Wednesday 27th. The number of rain days ranged from 21 days at Dublin Airport to 31 days at Valentia Observatory, Co Kerry. The number of wet days* ranged from 13 days at Phoenix Park, Co Dublin to 27 days at Belmullet, Co Mayo. The number of very wet days* ranged from 1 day at both Dublin Airport and Casement Aerodrome, Co Dublin to 13 days at Newport, Co Mayo.
Rainfall % of 1981 – 2010 Monthly Average for December 2023 (Provisional) Total Monthly Rainfall (mm) for December 2023 (Provisional)
Temperature: Above average everywhere
All mean air temperatures across the country were above their LTA for the month. Deviations from mean air temperature ranged from 1.2 °C (7.6 °C , 7.9 °C mean temperature) at Malin Head, Co Donegal and Belmullet, Co Mayo respectively to 2.3 °C (7.7 °C mean temperature) at Phoenix Park, Co Dublin. Mean temperatures for the month ranged from 6.2 °C (1.9 °C above its LTA) at Knock Airport, Co Mayo to 9.6 °C (1.6 °C above its LTA) at Sherkin Island, Co Cork. The month’s highest temperature was reported at Moore Park, Co Cork on Sunday 24th with a temperature of 14.4 °C. The month’s lowest air minimum was recorded on Friday 1st at Mount Dillon, Co Roscommon with -5.8 °C while the lowest grass minimum was -9.4 °C reported at both Mullingar, Co Westmeath and Mount Dillon, Co Roscommon, also on Friday 1st. All stations reported ground frost during the month. The number of days with ground frost ranged from 3 days at Roche’s Point, Co Cork to 12 days at Mount Dillon, Co Roscommon. More than half of stations reported air frost. The number of days with air frost ranged from zero days at Sherkin Island, Co Cork to 6 days at both Athenry, Co Galway and Mount Dillon, Co Roscommon.
Daily maximum temperatures for December 2023 at Valentia Observatory, Co Kerry, Dublin Airport, Co Dublin and Belmullet, Co Mayo
Sunshine: Highest in the South
Percentage of LTA sunshine values were variable (where available) across the country. Percentage of monthly sunshine values ranged from 86% (monthly sunshine total of 41.1 hours) at Casement Aerodrome, Co Dublin to 95% (monthly sunshine total of 42.8 hours) at Shannon Airport, Co Clare. Monthly sunshine totals ranged from 19.8 hours (No LTA comparison*) at Belmullet, Co Mayo to 62.3 hours (No LTA comparison*) at Cork Airport, Co Cork. The highest number of daily sunshine hours recorded this month was 7.1 hours at both Shannon Airport, Co Clare and Cork Airport, Co Cork on Monday 4th. The number of dull days* ranged from 11 days at Dublin Airport, Co Dublin to 19 days at Valentia Observatory, Co Kerry.
Wind: Storm force winds reported during storm Fergus. Storms Elin, Gerrit and Geraldine brought strong gales
Monthly mean wind speeds ranged from 7.6 knots (14.1 km/h) at Ballyhaise, Co Cavan to 20.3 knots (37.6 km/h) at Mace Head, Co Galway. Gales were reported on eighteen days during December. Strong gales were reported on Friday 8th, Saturday 9th during storm Elin, Sunday 10th during storm Fergus, Wednesday 27th during storm Gerrit, Thursday 28th during storm Gerrit and Saturday 30th during storm Geraldine. Storm force winds were reported on Sunday 10th at Mace Head, Co Galway during storm Fergus. The number of days with gales ranged from zero days at Mullingar, Co Westmeath to 12 days at both Mace Head, Co Galway and Malin Head, Co Donegal. The number of days with up to strong gales ranged from zero days at most stations to 4 days at Mace Head, Co Galway. The month’s highest gust was reported at Sherkin Island, Co Cork on Wednesday 27th during storm Gerrit with 64 knots (119 km/h). The month’s highest 10-minute mean wind speed was 49 knots (90 km/h) at Mace Head, Co Galway on Sunday 10th during storm Fergus.
Airmass Analysis chart 12 UTC 09 December 2023 with storm Elin and Fergus
The full report is available at https://www.met.ie/climate/past-weather-statements
December 2023 extreme values at synoptic stations
Recent Decembers in Ireland:
- 2016: Nearly all stations reported below Long-Term Average (LTA) for rainfall and all stations reported above LTA mean temperatures.
- 2017: Rainfall was above average at most stations. The majority of mean air temperatures were above average and sunshine totals were below overall. Storm Dylan brought storm force winds.
- 2018: Many stations were near normal for rainfall, but above normal in the South. All mean air temperatures across the country were above while all stations had below-average sunshine totals. Storm Deirdre brought strong gale-force winds.
- 2019: Monthly rainfall totals were variable across the country. Mean air temperatures were above everywhere and all stations had above-average sunshine totals. Storm force winds were reported during Storm Elsa and Storm Atiyah.
- 2020: Rainfall was above average. Temperatures were below in most places and sunshine totals were above everywhere. Strong gale-force winds were reported during Storm Bella.
- 2021: The majority of monthly rainfall totals were above average. All mean air temperatures were above and sunshine totals were variable. violent storm force 11 winds were reported during Storm Barra.
- 2022: The majority of monthly rainfall totals and all mean air temperatures were below average. Sunshine totals were above average.
*Issued by Met Éireann on Wednesday 3rd January 2024. This report is based on available preliminary data from 25 principal weather stations operated by Met Éireann. Synoptic station data is midnight to midnight UTC. Long-Term Averages (LTAs) and “average” refer to the period 1981-2010. A wet day is a day with 1.0 mm or more of rainfall. A dull day is a day with less than 0.5 hours of sunshine. A very wet day is a day with 10.0 mm or more of rainfall. Climatological dry periods – An absolute drought is a period of 15 or more consecutive days to none of which is credited 0.2 mm or more of precipitation. A partial drought is a period of at least 29 consecutive days, the mean daily rainfall of which does not exceed 0.2 mm. A dry spell is a period of 15 or more consecutive days to none of which is credited 1.0 mm or more of precipitation (i.e. daily tot < 1.0 mm). A heatwave occurs where there are 5 consecutive days or more with maximum temperature over 25°C (that is, a daily maximum screen air temperature > 25° C). *Sunshine data is from the Autosol Network. LTAs for these sites are currently not used for comparison purposes. For more information, contact Met Éireann at 01-8064200 or e-mail: enq@met.ie