Climate Statement for October 2021
Recent Octobers in Ireland: In the most recent and previous Octobers, the weather was typically changeable with a few storm events. October 2016 was mainly influenced by anticyclonic conditions allowing for predominantly dry settled conditions and no strong gales or storms reported. October 2017 brought the memorable ex-Hurricane Ophelia and then Storm Brian with violent storm force winds and strong gales reported at many stations throughout the country. October 2018 was a cool, dry month with above average sunshine values and the major weather event that month being Storm Callum which led to widespread heavy rain on the 12th and 13th. October 2019 was mainly sunny and cool but wet in the South, ex-hurricane Storm Lorenzo brought unsettled weather at the start of the month. October 2020 was predominantly cool, wet, and windy and storm force winds were reported during Storm Aiden which developed towards the latter stages of the month. Storm Aiden, on Saturday 31 October 2020, is the last time storm force winds were observed across Ireland.
Mild. Wet, especially in the South and West. Sunny in the South and East
October 2021 was mild and wet overall with Atlantic depressions to the west and northwest of Ireland dominating and keeping the airflow mostly between southerly and westerly. The first week saw low-pressure to the northwest steer Atlantic weather fronts across the country from the west and southwest, interspersed with showery periods and sunny spells. A deep area of low-pressure, containing the remnants of ex hurricane Sam, stalled to the west of Ire-land towards the end of the first week. This steered a very warm and moist southerly airflow across the country with trailing weather fronts, which brought some very heavy falls of rain, especially in the West and Southwest on the 8th and 9th. The Atlantic depressions stayed further away to the west of Ireland between the 10th and 15th, allowing high pressure to build over the country from the south, keeping it mostly dry. As the high pressure pulled away to the east at the beginning of the third week, low-pressure systems moved closer to Ireland once again, bringing bands of rain and showers from the south and west on most days up to the end of the month. An active and slow moving weather front gave some very heavy and widespread falls rain on the 27th and 28th, especially in the South. The month finished with a deep area of low-pressure bringing widespread wet and windy weather across the country on the 31st as it passed close to the Northwest of Ireland.
Rainfall: Above average in most places, wettest in the South and West
The majority of monthly rainfall totals were above their Long-Term Average (LTA). Percentage of monthly rainfall values ranged from 78% (monthly rainfall total of 81.1 mm) at Gurteen, Co Tipperary to 172% (monthly rainfall total of 187.0 mm) at Roche’s Point, Co Cork. Monthly rainfall totals ranged from 75.2 mm (95% of its LTA) at Phoenix Park, Co Dublin to 265.7 mm (151% of its LTA) at Newport, Co Mayo (its wettest October since 2011). The highest daily rain-fall total was 64.7 mm at Valentia Observatory, Co Kerry on Friday 8th. The number of rain days ranged from 18 days at Casement Aerodrome, Co Dublin to 28 days at a few stations. The number of wet days1 ranged from 13 days at Dublin Airport, Co Dublin to 25 days at both Newport, Co Mayo and Malin Head, Co Donegal. The number of very wet days3 ranged from 1 day at Gurteen, Co Tipperary to 11 days at Newport, Co Mayo. Sherkin Island, Co Cork had its wettest October since 1988 with 205.8 mm (161% of its LTA). Both Valentia Observatory, Co Kerry (264.9 mm, 150% of its LTA) and Belmullet, Co Mayo (222.4 mm, 152% of its LTA) had their wettest October since 2000. Cork Airport, Co Cork had its wettest October since 2005 with 197.6 mm (143% of its LTA).
Temperature: Above average everywhere
All mean air temperatures across the country were above their Long-Term Average (LTA) for the month. Deviations from mean air temperature ranged from 0.8 °C at both Sherkin Island, Co Cork (12.8 °C , the month’s highest mean temperature) and Valentia Observatory, Co Kerry (12.4 °C mean temperature) to 2.1 °C (12.3 °C mean temperature) at Phoenix Park, Co Dublin (its warmest October since 2011). Mean temperatures for the month were lowest at Knock Airport, Co Mayo with 10.3 °C (1.4 °C above its LTA). The month’s highest temperature was reported at Phoenix Park, Co Dublin on Thursday 7th with a tempera-ture of 20.4 °C (its highest max temperature for October since 2011). Both the month’s lowest air and grass minimum temperature were recorded on Friday 15th at Markree, Co Sligo. The lowest air minimum was 0.2 °C while the lowest grass minimum was -4.0 °C. There was no air frost reported this month. Less than half of stations reported ground frost. The number of days with ground frost ranged from zero days at a few stations to 9 days at Markree, Co Sligo. Three stations had their warmest October since 2001. These were Dublin Airport, Co Dublin (11.9 °C mean temperature, 1.6 °C above its LTA), Ballyhaise, Co Cavan (11.4 °C mean Temperature (1.3 °C above its LTA) and Mullingar, Co Westmeath (11.4 °C mean temperature, 1.9 °C above its LTA).
Sunshine: Highest in the South and East
All available sunshine totals were above their Long-Term Average (LTA). Percentage of monthly sunshine values ranged from 106% (monthly sunshine total of 108.2 hours) at Casement Aerodrome, Co Dublin to 110% (monthly sunshine total of 100.3 hours) at Shannon Airport, Co Clare. Monthly sunshine totals ranged from 75.4 hours (No LTA comparison*) at Malin Head, Co Donegal to 111.9 hours (No LTA comparison*) at Dublin Airport, Co Dublin. The high-est number of daily sunshine hours recorded this month was 9.9 hours at Johnstown Castle, Co Wexford on Sunday 10th. The number of dull days2 ranged from 5 days at Dublin Airport, Co Dublin to 13 days at Johnstown Castle, Co Wexford.
Wind: Strong gales reported
Monthly mean wind speeds ranged from 5.3 knots (9.8 km/h) at Moore Park, Co Cork to 15.6 knots (28.9 km/h) at Mace Head, Co Galway. Gales were reported on 9 days during the month with up to strong gale winds reported on Sunday 31st. The number of days with gales ranged from zero days at Dublin Airport, Co Dublin to 4 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 1 day at Mace Head, Co Galway. Both the month’s highest gust and 10-minute mean wind speed was reported at Mace Head, Co Galway on Sunday 31st. The highest gust was 54 knots (100 km/h) while the month’s highest 10-minute mean wind speed was 42 knots (78 km/h).
EXTREME VALUES AT SYNOPTIC STATIONS
Rainfall Highest total: 265.7 mm at Newport, Co Mayo (151% of its LTA) (its wettest October since 2011)
Lowest total: 75.2 mm at Phoenix Park, Co Dublin (95% of its LTA)
Highest daily rainfall: 64.7 mm at Valentia Observatory, Co Kerry (37% of its monthly LTA) on Fri 8th
Temperature Highest mean monthly temperature: 12.8°C at Sherkin Island, Co Cork (0.8°C above its LTA)
Lowest mean monthly temperature: 10.3°C at Knock Airport, Co Mayo (1.4°C above its LTA)
Highest Air temperature: 20.4°C at Phoenix Park, Co Dublin (6.1°C above its LTA) on Thu 7th (its
highest max temperature for October since 2011)
Lowest air temperature: 0.2°C at Markree, Co Sligo (5.6°C below its LTA) on Fri 15th
Lowest grass minimum: -4.0°C at Markree, Co Sligo on Fri 15th
Sunshine Highest monthly total: 111.9 hrs (daily mean 3.61 hrs/day) at Dublin Airport, Co Dublin
Lowest monthly total: 75.4 hrs (daily mean 2.43 hrs/day) at Malin Head, Co Donegal
Highest daily sunshine: 9.9 hours at Johnstown Castle, Co Wexford on Sun 10th
The full report is available here