Sunshine records broken during warm May

Ireland enjoyed a notably warm, dry and sunny May in 2025, with temperatures well above average and rainfall amounts well below.

Early figures from Met Éireann show that May 2025 was among the warmest on record, continuing a clear trend of warmer springs in recent years.

One of Ireland’s Warmest Mays on Record

The provisional average temperature for the month came in at 12.54°C—making it the sixth warmest May in 126 years of Irish records. It marks yet another year in a growing pattern: all seven of the warmest Mays have occurred since 2008. While 2024 still tops the list, May 2025 was not far behind, coming in 1.85°C above the 20th-century average and 1.21°C above the 1991–2020 norm.

Warm conditions were felt across the country, with particularly high temperatures recorded in the South and West. Shannon Airport experienced its warmest May on record at 14.2°C, 2.0°C above average. Knock Airport saw the largest deviation from normal, with a mean of 12.5°C—2.3°C above average.

The warmest day of the month was Tuesday 13th, when Newport, Co Mayo reached a balmy 24.8°C. Despite the warmth, chilly nights weren’t completely absent—Mount Dillon in Co Roscommon recorded a low of -0.9°C early in the month.

Five stations across the country broke their all-time May temperature records, including Cork and Knock airports, and fourteen stations recorded their highest-ever May mean maximum temperatures.

A Bright Month with Sunshine in Abundance

Sunshine was another big story in May 2025, with most parts of the country enjoying well above-average hours of sunshine. Shannon Airport and Cork Airport both recorded their sunniest calendar month ever, with Cork topping out at 290.4 hours.

Johnstown Castle in Co Wexford had the highest total of all, with 298.8 hours of sunshine. Sunshine levels were up to 158% of normal in places, with only a handful of dull days recorded nationwide. Casement Aerodrome reported just one dull day, while even normally cloud-prone locations like Valentia Observatory had only five.

Dublin Airport, Casement Aerodrome and several others recorded their second sunniest May since records began.

Another Exceptionally Dry May

Rainfall totals were well down, making this the fourth May in a row with below-average rainfall across Ireland. Provisional data suggests the country averaged around 56mm of rain—just 70% of the long-term norm.

Roches Point in Co Cork had its driest May on record, with only 19.9mm of rain (31% of average). Most locations reported significantly fewer wet days than usual, with many areas in the South and Midlands seeing prolonged dry spells.

In total, 20 weather stations recorded official “climatological dry spells” (15+ days with less than 1.0mm of rain), with some lasting over three weeks. Eleven stations experienced absolute drought conditions, and two reported partial droughts lasting 30 days.

The highest single-day rainfall total came at Casement Aerodrome in Dublin, with 19.3mm falling on Tuesday 20th.

Wind: Generally Calm, With Just One Gale Event

May’s settled weather meant winds were mostly light, thanks to the persistent presence of high pressure to the north. Monthly mean wind speeds ranged from 4.8 knots in Ballyhaise, Co Cavan to 10.8 knots at Mace Head, Co Galway.

There was just one report of gale-force winds—on Sunday 25th at Mace Head. The strongest gusts, reaching 43 knots (80 km/h), were recorded at both Roches Point and Malin Head late in the month.

A Month Dominated by High Pressure

Weather patterns throughout May were heavily influenced by a dominant area of high pressure centred mostly to the north of Ireland. The first three weeks were largely dry and sunny, with only brief interruptions from passing fronts.

A slack area of low pressure brought some instability and scattered thunderstorms between the 11th and 14th, but rainfall remained low overall. Another bout of thunderstorm activity occurred around the 19th–20th, linked to cooler air aloft and warm surface conditions.

Atlantic fronts finally broke through by the final week of the month, bringing a return to more typical late spring weather, with a mix of sunshine and showers and a cooler westerly flow.

Marine Heatwave Intensifies

One knock-on effect of the warm, settled conditions was the intensification of a marine heatwave off Ireland’s south and west coasts. Sea surface temperatures, already running high in April, continued to climb under persistent sunshine and slack easterly winds.