Recent Aprils in Ireland:
- 2016: Changeable and unsettled early on, but settled for the second half of the month. 1981-2010 Long-Term Average (LTA) rainfall values were variable and all stations reported below average air temperatures.
- 2017: Mild and dry everywhere. All rainfall totals were below their LTA with temperatures near or above their LTA.
- 2018: Unsettled, dull and wet. The majority of monthly rainfall totals and air temperatures were above their LTA and most available sunshine totals were below their LTA.
- 2019: Above average temperatures and rainfall for most stations with Storm Hannah bringing storm force winds this month.
- 2020: Very dry, mild and sunny. Rainfall totals were below average everywhere, all air temperatures across the country and all available sunshine totals were above their LTA.
- 2021: Very dry, cool and sunny. All rainfall totals and nearly all air temperatures were below their LTA while all available sunshine totals were above their LTA.
Mild, dry and sunny overall
April was a relatively dry month with high pressure, centred mostly to the north of Ireland, in control. The beginning of the first week saw bands of mostly light rain or showers crossing the country from the northwest, as they circled around an area of high pressure to the west of Ireland. The centre of a rela-tively deep area of low-pressure moved close to the north of the country at the end of the first week, bringing further rain or showers, along with the windi-est period of the month. A cooler air mass at the beginning of the second week brought drier conditions with widespread frost at night. A low-pressure system to the west of Ireland, named storm Evelyn by the Portuguese met service, brought a milder airflow, along with bands of rain or showers from the southwest between the 10th and 12th. Further frontal rain or showers pushed in from the west towards the end of the second week and beginning of the third week, but amounts stayed relatively low. On Sunday 17th, an active cold front gave widespread and prolonged falls of rain as it pushed slowly across the country from the west. For the remainder of the month, high pressure to the north dominated, bringing an easterly airflow with mostly dry conditions. It was cool at times, especially in the East, but there was also several warm and sunny days, especially in the West and Northwest. The final day of the month saw a shallow area of low-pressure bringing widespread frontal rain down from the northwest.
Rainfall: Below average in most places, driest in the East
Nearly all rainfall totals were below their 1981-2010 Long-Term Average (LTA) for the month. Percentage of monthly rainfall values ranged from 43% (monthly rainfall total of 33.2 mm) at Mace Head, Co Galway to 130% (monthly rainfall total of 84.2 mm) at Malin Head, Co Donegal. Monthly rainfall totals ranged from 28.1 mm (52% of its LTA) at Dublin Airport, Co Dublin to 85.2 mm (109% of its LTA) at Markree, Co Sligo (its wettest April since 2009). The highest daily rainfall total was 25.8 mm at Roche’s Point, Co Cork on Sunday 17th. The number of rain days ranged from 10 days at Oak Park, Co Carlow to 21 days at both Malin Head, Co Donegal and Belmullet, Co Mayo. The number of wet days1 ranged from 7 days at Dunsany, Co Meath to 16 days at a few stations. The number of very wet days3 ranged from zero days at a few stations to 4 days at Valentia Observatory, Co Kerry. Fifteen stations had dry spells6 between 16th March and 5th April lasting between 15 and 21 days. Six stations had absolute droughts4 between 18th March and 2nd April lasting between 15 and 16 days. These were Shannon Airport, Co Clare, Athenry, Co Galway, Mace Head, Co Galway, Valentia Observatory, Co Kerry, Mount Dillon, Co Ros-common and Markree, Co Sligo.
Temperature: Above average at most stations, warmest in the West
Nearly all mean air temperatures were above their Long-Term Average (LTA) for the month. Deviations from mean air temperature ranged from -0.6 °C (7.6 °C, the month’s lowest mean temperature) at Dublin Airport, Co Dublin to 0.9 °C (8.3 °C , 10.0 °C mean temperature) at Knock Airport, Co Mayo and New-port, Co Mayo respectively. The highest mean temperatures was 10.0 °C at Newport, Co Mayo (0.9 °C above its LTA). The month’s highest temperature was reported at Phoenix Park, Co Dublin on Friday 15th with a temperature of 18.5 °C. The month’s lowest air minimum was recorded on Sunday 3rd at Mullin-gar, Co Westmeath with -4.6 °C while the lowest grass minimum was -10.1 °C reported at Mount Dillon, Co Roscommon on Friday 1st. All stations reported ground frost during the month. The number of days with ground frost ranged from 4 days at Sherkin Island, Co Cork to 22 days at Mount Dillon, Co Ros-common. More than half of stations reported air frost. The number of days with air frost ranged from zero days at a few stations to 11 days at Dublin Airport, Co Dublin.
Sunshine: Sunniest in the Northwest
All available sunshine totals were above their Long-Term Average (LTA). Percentage of monthly sunshine values ranged from 113% (monthly sunshine total of 174.3 hours) at Shannon Airport, Co Clare to 115% (monthly sunshine total of 175.2 hours) at Casement Aerodrome, Co Dublin. Monthly sunshine totals ranged from 152.1 hours (No LTA comparison*) at Valentia Observatory, Co Kerry to 193.2 hours (No LTA comparison*) at Malin Head, Co Donegal. The highest number of daily sunshine hours recorded this month was 14.1 hours at Malin Head, Co Donegal on Wednesday 27th. The number of dull days ranged from 5 days at Shannon Airport, Co Clare to 8 days at Gurteen, Co Tipperary.
Wind: Strong gales reported
Monthly mean wind speeds ranged from 5.9 knots (10.9 km/h) at Ballyhaise, Co Cavan to 13.7 knots (25.4 km/h) at Malin Head, Co Donegal. Gales were reported on the 5th, 6th, 7th and 11th with up to strong gale winds reported on Wednesday 6th. The number of days with gales ranged from zero days at a few stations to 4 days at Malin Head, Co Donegal. The number of days with strong gales ranged from zero at most stations to 1 day at Mace Head, Co Gal-way. The month’s highest gust was reported at both Mace Head, Co Galway and Newport, Co Mayo both on Wednesday 6th with 59 knots (109 km/h). The highest 10-minute wind speed was 45 knots (83 km/h) reported at Mace Head, Co Galway on Wednesday 6th.
The full report is available here