April was a very dry month with cold, polar air over the country on several occasions through the month, leading to below average temperatures everywhere, according to the latest monthly bulletin from Met Éireann.
The cool, dry conditions, while cold, also brought above average sunshine.
The first week saw high pressure to the northwest build towards Greenland, allowing the very cold polar air mass to sweep south over the island. This brought rain or showers, some wintry, towards the end of the first week but amounts stayed low.
The cold northerly airflow re-established during the second week and so there were occasional showers, again some wintry and with hail, but the week finished dry as high pressure developed directly over Ireland. The third week saw some weak weather fronts cross from the west, but rainfall amounts again stayed low, especially in the south and east.
At the beginning of the fourth week, high pressure built over Ireland and gradually moved to the north, bringing a dry easterly airflow over the country for most of the week. This brought a few warm days, especially in the midlands and west, before low pressure moved south over the UK towards the end of the month, establishing a cool and showery northeasterly airflow over Ireland.
Rainfall
The monthly rainfall totals across the country were all below their long-term average, ranging from 17 per cent at Johnstown Castle, Co Wexford, to 59 per cent at Belmullet, Co Mayo. The highest daily rainfall during April was 9.3mm at Roche’s Point, Co Cork, on Thursday April 29th. The number of rainy days ranged from 8 days at Johnstown Castle to 17 days at both Belmullet, and Ireland West International Airport, Co Mayo.
Four weather stations had their driest April on record. Oak Park, Co Carlow, had 14.4mm or 26 per cent of its long-term average, its lowest record in 15 years. Sherkin Island, Co Cork, had 13.5mm or 18 per cent of its long-term average – its lowest level of rainfall in 48 years. Johnstown Castle, Co Wexford, had 12.3mm or 17 per cent of its long-term average rainfall for April, representing its driest April in 80 years.
Cool temperatures
In terms of temperature, April was cool almost everywhere. Deviations from average air temperature ranged from -2.5 degrees at Dublin Airport, which suffered its coldest April on record – based on a duration of 78 years. The month’s highest mean temperature of 9.1 degrees was recorded at Valentia Observatory, Co Kerry (0.2 degrees below its long term average). The month’s highest temperature was also reported at Valentia Observatory, Co Kerry on Thursday April 1st, with a temperature of 21.2 degrees.
All available sunshine totals were above their long-term averages, with 131 per cent or 209.8 hours, recorded at Cork Airport, to 141 per cent – a monthly sunshine total of 218.5 hours at Shannon Airport, Co Clare.
Average wind speeds ranged from 4.9 knots (9.1 kmph) at Ballyhaise, Co Cavan to 12.4 knots (23.0 kmph) at Malin Head, Co Donegal. Gales were reported on Monday April 5th. The number of days with gale force winds ranged from zero days at most stations to 1 day at Malin Head, Co Donegal. There were no strong gales or storms reported during April. Both the month’s highest gust and 10-minute mean wind speed were reported at Malin Head, Co Donegal on Monday April 5th.
