September 2026 has been described as "provisionally the second warmest on record for Ireland", with the average temperature of 15.22°C ranking it behind only 2021’s average of 15.27°C.

The latest Met Éireann Climate Statement reported "significantly higher than average temperatures" across the country for September.

These levels made the month 1.62° warmer than the 1991-2020 average, and 2.29° above the average for 1961-1990.

According to Met Éireann, six of the 10 warmest Septembers on record have occurred since 2001, while none of the 10 coolest have occurred during that period. 

Very warm, wet and dull for most

September 2026 was significantly warmer than average everywhere, especially in the east, Met Éireann said.

It was also wetter and duller than average in most places with frequent rain or showers.

Low pressure to the north and high pressure to the south through most of the month resulted in a predominantly mild, mobile Atlantic airflow between southerly and westerly.

Occasionally, high pressure to the south moved north and brought some short dry periods.

On other occasions, low pressure to the north moved closer and brought some active weather fronts across the country from the west or south-west with heavy rain in places.

Rainfall above average in most places

The majority of monthly rainfall totals were above their 1991-2020 Long-Term Average (LTA).

Percentage of monthly rainfall values ranged from 99% (76.6 mm) at Shannon Airport, Co. Clare to 163% (110.6 mm) at Oak Park, Co. Carlow.

Monthly rainfall totals ranged from 73.8 mm (100% of its LTA) at Roches Point, Co. Cork to 172.3 mm (131% of its LTA) at Newport, Co. Mayo.

The highest daily rainfall total was 38.6 mm at Oak Park, Co. Carlow on September 27.

The number of rain days ranged from 17 days at Dublin Airport, Co. Dublin to 28 days at several stations.

Temperature above average everywhere

All mean air temperatures across the country were above their LTA for the month.

Mean temperatures for the month ranged from 13.4° (1.3° above its LTA) at Knock Airport, Co. Mayo to 15.8° (1.6° above its LTA) at Shannon Airport, Co. Clare (its warmest September on record (length 81 years).

The month’s highest temperature was reported at Phoenix Park, Co. Dublin on Monday 14 with a temperature of 25.2°.

The month’s lowest air and grass minimum temperatures were recorded on September 28.

No air frost was reported for September.

Less than half of stations reported ground frost.

The number of days with ground frost ranged from zero days at most stations to three days at Mount Dillon, Co. Roscommon.

Along with Shannon Airport, seven other stations reported their warmest September on record.

Five stations reported their joint warmest September on record, three tied with September 2021 - the warmest September on record for Ireland.

Among the record-breaking stations are Phoenix Park and Dublin Airport with records going back 127 and 84 years respectively.

The lowest temperature reported this September was 11.3° at Mace Head, Co. Galway.

Sunshine: Dull overall

Met Éireann reported a dull month overall with only one station reporting sunshine values above average.

Percentage of monthly sunshine values ranged from 99% (117.3 hours) at Shannon Airport, Co. Clare to 106% (the month’s highest monthly sunshine total of 134.0 hours) at Casement Aerodrome, Co. Dublin.

Monthly sunshine totals were lowest at Valentia Observatory, Co. Kerry with 67.3 hours.

The highest number of daily sunshine hours recorded this month was 10.6 hours at Dublin Airport on September 20.

Wind: Gales reported on four days

Monthly mean wind speeds ranged from 5.4 knots (10.0 km/h) at Moore Park, Co. Cork to 17.7 knots (32.8 km/h) at Mace Head, Co. Galway.

Gales were reported on September 6, September 11, September 17 and September 29.

The number of days with gale force winds ranged from zero days at a few stations to three days at Belmullet, Co. Mayo.

There were no strong gales or storms reported this month.

Both the month’s highest gust and 10-minute mean wind speed were reported on September 29.

The highest gust was 56 knots (104 km/h) reported at Valentia Observatory, Co. Kerry while the month’s highest 10-minute mean wind speed was 40 knots (74 km/h) reported at Belmullet, Co. Mayo.

Eight stations reported their highest mean wind speed for September since 2011.