Mild overall, dry in the South and East
High pressure that built over Ireland from the south at the end of February continued to dominate through the first week of March. This brought a mixture of some dull days with low cloud along with some brighter days with sunny spells. It stayed mostly dry overall, but cool with frost and fog in many places at night. The high pressure moved away to the south at the beginning of the second week, allowing Atlantic weather fronts to encroach from the west. A westerly airflow with low pressure to the north took control for the rest of the second week. This brought bands of rain and showers across the country on most days up to the 14th, with thundery falls in places. High pressure, which built from the south again at the beginning of the third week, brought milder weather and kept it mostly dry up to the 22nd. During the fourth week, pressure stayed relatively high, but low pressure to the north brought several weather fronts and showers across the country from the west, with the bulk of the rain falling in the western half of the country. There was a brief cold intrusion from the northwest on Friday the 26th, where some of the showers turned wintry. The month finished mild overall and mostly dry in the South and East, however slow moving weather fronts continued to bring pulses rain to the West and North.
Rainfall: Wet in the Northwest, dry elsewhere
The majority of monthly rainfall totals across the country were below their Long-Term Average (LTA). Percentage of monthly rainfall values ranged from 41% (monthly rainfall total of 32.7 mm) at Johnstown Castle, Co Wexford to 138% (monthly rainfall total of 140.3 mm) at Claremorris, Co Mayo. Monthly rainfall totals ranged from 29.6 mm (58% of its LTA) at Casement Aerodrome, Co Dublin to 141.1 mm (100% of its LTA) at Newport, Co Mayo. The highest daily rainfall total was 26.4 mm at Athenry, Co Galway on Sunday 28th. The number of rain days ranged from 11 days at Johnstown Castle, Co Wexford to 25 days at Belmullet, Co Mayo. The number of wet days¹ ranged from 7 days at Dublin Airport to 19 days at Newport, Co Mayo. The number of very wet days³ ranged from zero days at a few stations to 6 days at Claremorris, Co Mayo. Eight stations had their driest March since 2012, these were Oak Park, Co Carlow, Dublin Airport, Co Dublin, Sherkin Island, Co Cork, Roches Point Co Cork, Dunsany, Co Meath, Johnstown Castle, Co Wexford, Casement Aerodrome, Co Dublin and Cork Airport, Co Cork.
Temperature: Cool first half, mild second half
Nearly all mean air temperatures were above their Long-Term Average (LTA) for the month. Deviations from mean air temperature ranged from -0.2 °C (7.7 °C mean temperature) at Mace Head, Co Galway to 1.3 °C (8.0 °C mean temperature) at Phoenix Park, Co Dublin. Mean temperatures for the month ranged from 6.2 °C (0.6 °C above its LTA) at Knock Airport, Co Mayo to 8.5 °C (0.1 °C above its LTA) at Sherkin Island, Co Cork. The month’s highest temperature was reported at Mount Dillon, Co Roscommon on Tuesday 30th with a temperature of 17.6 °C. The month’s lowest air minimum was recorded on Friday 5th at Dublin Airport, Co Dublin with -3.5 °C while the lowest grass minimum was -9.2 °C reported at Cork Airport, Co Cork on Sunday 7th (its lowest March grass minimum since 2001). More than half of stations reported ground frost. The number of days with ground frost ranged from zero days at Sherkin Island, Co Cork to 15 days at Oak Park, Co Carlow. More than half of stations reported air frost. The number of days with air frost ranged from zero days at Mace Head, Co Galway to 5 days at both Oak Park, Co Carlow and Dublin Airport, Co Dublin.
Sunshine: Highest in the East and Southeast
Percentage of Long-Term Average (LTA) sunshine values were variable across the country. Percentage of monthly sunshine values ranged from 77% (monthly sunshine total of 77.6 hours) at Shannon Airport, Co Clare to 112% (monthly sunshine total of 114.1 hours) at Casement Aerodrome, Co Dub-lin. Monthly sunshine totals ranged from 69.1 hours (No LTA comparison*) at Malin Head, Co Donegal to 116.3 hours (No LTA comparison*) at Dublin Airport, Co Dublin. The highest number of daily sunshine hours recorded this month was 11.1 hours at Dublin Airport, Co Dublin on Tuesday 30th. The number of dull days² ranged from 7 days at both Dublin Airport and Casement Aerodrome, Co Dublin to 14 days at Valentia Observatory, Co Kerry.
Wind: Strong gales reported
Monthly mean wind speeds ranged from 6.5 knots (12.0 km/h) at Moore Park, Co Cork to 15.1 knots (28.0 km/h) at Mace Head, Co Galway. Gales were reported on 10 days during the month with up to strong gale winds reported on the 9th, 10th, 11th and 12th. The number of days with gales ranged from zero days at a few stations to 7 days at Mace Head, Co Galway. The number of days with up to strong gales ranged from zero at a most stations to 3 days at Sherkin Island, Co Cork, 2 days at Roches Point, Co Cork and 1 day at both Belmullet, Co Mayo and Mace Head, Co Galway. Both the month’s highest gust and 10-minute mean wind speed was reported at Sherkin Island, Co Cork. The highest gust was on Friday 12th with 68 knots (126 km/h) while the month’s highest 10-minute mean wind speed was 45 knots (83 km/h) on Wednesday 10th.
The full report is available here
Total Monthly Rainfall (mm) for March 2021 (Provisional)
Rainfall % of 1981 – 2021 Monthly Average for March 2021 (Provisional)