September 2026 was 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. Significantly higher than average temperatures across the country made it 1.62°C warmer than the 1991-2020 average, and 2.29°C above the average for 1961-1990. Low pressure to the north and high pressure to the south through most of the month resulted in a predominantly mild, mobile Atlantic airflow and frequent rain or showers.
Key National Figures:
- September 2026 was provisionally the second warmest on record, averaging 15.22 °C, just 0.05 °C below the record set in 2021
- Temperatures were 1.62 °C above the recent 1991 to 2020 average and nearly 2 °C warmer than September last year.
- Six of the ten warmest Septembers on record have occurred since 2001, while none of the ten coolest have occurred during that period.
- September 2026 was wetter than average, recording 116.8 mm of rainfall, or 117 % of the 1991 to 2020 average.
- Provisionally ranked the 38th wettest September on record, it was wetter than August 2026 but drier than September 2025.
September 2026 Climate Statement cover
Very warm, wet and dull for most
September 2026 was significantly warmer than average everywhere, especially in the East. 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 southwest with heavy rain in places. Several of the sunniest days, Tuesday 8th, Tuesday 15th and Wednesday 23rd followed cold fronts when slightly cooler Polar maritime air masses along with transient ridges of high pressure moved over the country. Several of the warmest days, Wednesday 2nd, Saturday 12th, Monday 14th and Monday 21st, when temperatures reached the mid-twenties in places, followed warm fronts when tropical maritime air masses moved over the country from the south or southwest. Heavy rain fell on Sunday 27th in the South and East as a secondary shallow low moved north and interacted with a cold front crossing the country from the west. A rapidly deepening and intense low pressure system moved north from the Azores on Monday 28th. The storm passed Ireland well to the west on Tuesday 29th moving north but brought widespread rain and strong winds along with a very warm tropical maritime airmass.
Rainfall: Above average in most places, wettest in the Southeast and Northwest
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 Sunday 27th. The number of rain days0 ranged from 17 days at Dublin Airport, Co Dublin to 28 days at a few stations. The number of wet days1 ranged from 12 days at Oak Park, Co Carlow to 24 days at both Newport, Co Mayo and Belmullet, Co Mayo. The number of very wet days3 ranged from 1 day at a few stations to 6 days at Newport, Co Mayo.
Total Monthly Rainfall (mm) for September 2026 (Provisional) and rainfall % of 1991 – 2020 Monthly Average for August 2026 (Provisional).
Temperature: Significantly above average everywhere, highest in the East
All mean air temperatures across the country were above their LTA for the month. Deviations from mean air temperature ranged from +0.9 °C at both Belmullet, Co Mayo (14.6 °C mean temperature) and Newport, Co Mayo (14.7 °C mean temperature) to +2.6 °C at Dublin Airport, Co Dublin (15.6 °C mean temperature). Mean temperatures for the month ranged from 13.4 °C (1.3 °C above its LTA) at Knock Airport, Co Mayo to 15.8 °C (1.6 °C 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 14th with a temperature of 25.2 °C. The month’s lowest air and grass minimum temperatures were recorded on Monday 28th. The lowest air minimum reported at Markree, Co Sligo with a temperature of 2.6 °C and the lowest grass minimum reported at Mount Dillon, Co Roscommon with -2.1 °C. There was no air frost reported this month. Less than half of stations reported ground frost. The number of days with ground frost ranged from zero days at most stations to 3 days at Mount Dillon, Co Roscommon. Along with Shannon Airport, seven other stations reported their warmest September on record and 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 at Mace Head, Co Galway this September was 11.3 °C. This is the highest overall monthly minimum temperature for September at any synoptic station on record. Five other stations also had their highest overall monthly minimum temperature for September on record. Ten stations had their highest mean minimum temperature for September on record while two stations in Dublin, Phoenix Park and Dublin Airport, had their highest mean maximum temperature for September on record.
Mean Temperature (°C) for September 2026 (Provisional) and difference from 1991-2020 LTA (°C) for September 2026 (Provisional)
Sunshine: Dull overall, sunniest in the East, dullest in the South and West
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 (No LTA comparison*). The highest number of daily sunshine hours recorded this month was 10.6 hours at Dublin Airport on Sunday 20th. The number of dull days2 ranged from 2 days at both Gurteen, Co Tipperary and Casement Aerodrome, Co Dublin to 11 days at both Valentia Observatory, Co Kerry and Belmullet, Co Mayo.
Hours of Bright Sunshine observed at nine stations for each day of the month of September 2026, grouped by province relative to the highest number of hours possible by end of month (shaded box).
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 report ed on Sunday 6th, Friday 11th, Thursday 17th and Tuesday 29th. The number of days with gale force winds ranged from zero days at a few stations to 3 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 Tuesday 29th. 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.
Full PDF report and charts are available here
September 2026 extreme values at synoptic stations.
Notes to Editor:
- *Issued by Met Éireann on Friday 2nd October 2026. This report is based on available preliminary data from 25 principal weather stations operated by Met Éireann. Synoptic station data is midnight to midnight UTC.
- Overnight highest minimum temperatures and tropical nights are measured 9am to 9am (09-09) according to WMO standards. A tropical night is the count of days when the daily minimum temperature, is greater than 20 °C (09-09).
- Long-Term Averages (LTAs) and “average” refer to the period 1991-2020 unless stated.
- A rain day is a day on which 0.2 mm or more of rainfall is measured. A wet day is a day with 1.0 mm or more of rainfall. A dull day is a day with less than 0.5 hours of sunshine. A very wet day is a day with 10.0 mm or more of rainfall.
- Climatological dry periods – An absolute drought is a period of 15 or more consecutive days to none of which is credited 0.2 mm or more of precipitation. A partial drought is a period of at least 29 consecutive days, the mean daily rainfall of which is less than or equal to 0.2 mm. A dry spell is a period of 15 or more consecutive days to none of which is credited 1.0 mm or more of precipitation (i.e. daily tot < 1.0 mm).
- A heatwave occurs where there are 5 consecutive days or more with maximum temperature over 25°C (that is, a daily maximum screen air temperature > 25° C).
- The ‘Island of Ireland’ dataset is 125 years long and runs between 1900 and 2023. For this dataset the long term averages from the 1961-1990 reference period are used for comparison as is standard for long-term climate change assessments.
- Sunshine data is from the Autosol Network. LTAs for these sites are currently not used for comparison purposes.
- For more information, please contact us at enq@met.ie.