September 2026 delivered an average temperature of 15.22°C across Ireland, making it provisionally the second warmest September on record, behind only 2021's 15.27°C, according to Met Éireann's latest Climate Statement.

The month ran 1.62°C warmer than the 1991-2020 average and 2.29°C above the 1961-1990 average. Six of the 10 warmest Septembers on record have occurred since 2001, while none of the 10 coolest have fallen in that period.

For farmers, the pattern matters as much as the headline figure. Warmth came wrapped in frequent rain, dull skies and four days of gales — a combination that keeps temperatures up but does little for harvesting, grazing conditions or soil trafficability.

How warm was it?

Every station in the network reported mean air temperatures above its long-term average (LTA), with the east seeing the largest anomalies.

Mean temperatures ranged from 13.4°C at Knock Airport, Co. Mayo (1.3° above its LTA) to 15.8°C at Shannon Airport, Co. Clare — that station's warmest September in an 81-year record.

Shannon was not alone. Seven other stations reported their warmest September on record, and five more reported their joint warmest. Three of those tied with September 2021, the warmest September on record for Ireland.

The record-breakers include Phoenix Park and Dublin Airport, whose records stretch back 127 and 84 years respectively.

The month's highest temperature reached 25.2°C at Phoenix Park on Monday, September 14. The lowest temperature reported was 11.3°C at Mace Head, Co. Galway, with the lowest air and grass minimums recorded on September 28.

No air frost was reported anywhere in September. Fewer than half of stations recorded ground frost, ranging from zero days at most stations to three days at Mount Dillon, Co. Roscommon.

How wet was it?

The majority of monthly rainfall totals came in above their 1991-2020 LTA, with Met Éireann describing a wetter and duller than average month in most places.

The spread was wide:

• 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 totals ran from 73.8 mm at Roches Point, Co. Cork (100% of LTA) to 172.3 mm at Newport, Co. Mayo (131% of LTA).
• The highest daily rainfall was 38.6 mm at Oak Park, Co. Carlow, on September 27.
• Rain days ranged from 17 at Dublin Airport to 28 at several stations.

Why the weather pattern settled as it did

Low pressure to the north and high pressure to the south dominated most of the month. That pressure set-up drove a mild, mobile Atlantic airflow from between southerly and westerly directions.

When the southern high pressure edged north, it brought short dry spells. When the northern low pressure moved closer, active weather fronts swept across the country from the west or south-west, delivering heavy rain in places.

What about sunshine and wind?

Sunshine was in short supply. Only one station recorded above-average sunshine. Monthly sunshine values ranged from 99% (117.3 hours) at Shannon Airport to 106% — and the month's highest total of 134.0 hours — at Casement Aerodrome, Co. Dublin. Valentia Observatory, Co. Kerry recorded the lowest total, at 67.3 hours. The sunniest single day brought 10.6 hours at Dublin Airport on September 20.

Wind added to the unsettled picture:

• Gales were reported on September 6, 11, 17 and 29.
• 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.
• Gale-days ranged from zero at a few stations to three at Belmullet, Co. Mayo.
• The month's highest gust hit 56 knots (104 km/h) at Valentia Observatory on September 29, with the highest 10-minute mean wind speed of 40 knots (74 km/h) at Belmullet the same day.

No strong gales or storms were reported. Eight stations recorded their highest mean wind speed for September since 2011.

Met Éireann's figure remains provisional until full quality control of station data is complete, so farmers should watch for the finalised statement and the October climate outlook when planning late-season fieldwork and grazing decisions.