A look back at the summer of 1976

The summer of 1976 is remembered in Ireland and the UK as a long, hot summer. While individual weather events occur within the context of natural climate variability, there is now clear and robust evidence that the world is warming and that human activities are the dominant cause of recent climate change.  

Monday, June 22nd 2026

Since 1976 there have been two summers with higher overall average temperatures in Ireland, 1995 and 2025 (figure 1). However, a more complete analysis is needed to show why 1976 is only the third warmest summer, considering how it sits in folklore as such a long hot summer. Here we show a comparison between Ireland’s three warmest summers.  

Figure 1: Top 10 warmest summers on record for Ireland, showing the overall average summer temperature for each year and the anomaly (°C) with respect to Ireland’s 1991-2020 long term average.

The Irish Summers of 1976, 1995 and 2025   

Synoptic Scale Differences: 

The large-scale atmospheric patterns during the summers of 1976 and 1995 were very similar, with anomalously high geopotential height sitting directly over and just to the north of Ireland (figure 2). This indicates that both those summers were dominated by high pressure, leading to sunny and dry summers overall. By contrast the summer of 2025 saw the highest anomalies for geopotential height to the south of Ireland, with low geopotential height anomalies to the north. This indicates that the summer of 2025 was more changeable, with high pressure to the south bringing warmer and drier weather at times, while low pressure to the north brought wetter and cloudier periods also. 

Figure 2: ERA5 500hPa Geopotential Height anomaly for the three warmest summers in Ireland. All data shown is for June, July, and August of the given year. Top left: 1976, top right: 1995, and bottom: 2025.

Temperature Measurements 

Maximum, mean and minimum temperatures each describe a different part of the temperature distribution, while rainfall adds the moisture context needed to interpret summer conditions. Together, these measurements give a fuller picture of the Irish summer climate record.   

• Maximum temperature shows daytime heating and helps track hot extremes, heat stress, fire weather and changes in daytime warming.  

• Minimum temperature shows night-time cooling and is important in summer for night-time heat stress.  

• Mean temperature summarises overall conditions, but can hide important changes, such as warmer nights, cooler days, or shifts in extremes.  

• Rainfall shows whether warmth occurred in dry or wet conditions. A hot, dry summer, a hot, wet summer and a cool, wet summer have very different impacts.  

• A Heatwave in Ireland 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 perceived “niceness” of a summer is not the same for everyone. The highest temperatures and driest conditions may suit some activities, but they can also bring heat stress, drought pressure and difficult conditions for farming, water supply, nature and health. 

Key figures from summer 1976: 

• The longest heatwave on record for Ireland was 14 days from Saturday 14th to Friday 27th August 1976 inclusive at both Birr Castle, Co Offaly (highest 28.2 °C) and Ballybrittas, Co Laois (highest 29.5 °C). 

• Earlier that summer, there was a heatwave lasting nine Days at Kilkenny, Co Kilkenny starting Sunday 27 June 1976, where temperatures rose to 31.5 °C on Tuesday 29 June 1976. 

• The driest summer on record (length 85 years) was in 1976, with an average rainfall of 139.6 mm. 

• The highest temperature of the 20th century in Ireland was 32.5 °C, recorded at Boora, Co. Offaly on Tuesday 29 Jun 1976.  

• There was 21 consecutive days > 20.0 °C at Kilkenny, beginning Saturday 7 August 1976. 

Key figures from summer 1995: 

• There was a heatwave lasting eight days at Shannon Airport, Co Clare from Friday 23 June 1995 and temperatures rose to 30.2 °C on Thursday 29 June 1995. 

• Later that summer, there was a heatwave lasting six days at Shannon Airport, Kilkenny and Birr Castle, Co Offaly. Temperatures rose to 30.8 °C at Kilkenny on Wednesday 2 August 1995. 

• There was 34 consecutive days > 20.0 °C at Casement Aerodrome, Co Dublin beginning Monday 24 July 1995. 

• The second driest summer on record (length 85 years) was in 1995 with an average rainfall of 143.1 mm. 

Key figures from summer 2025: 

• The were zero heatwaves in summer 2025. There were four consecutive Summer Days (> 25 °C) at Mount Dillon, Co Roscommon, with temperatures rising to 31.1 °C here on Saturday 12 July 2025. 

• There were 20 consecutive days > 20.0 °C at Moore Park, Co Cork beginning Thursday 7 August 2025. 

• It was the 57th driest summer on record (length 85 years) with an average rainfall of 278.3 mm. 

Table 1. Table. National climate averages for temperatures and rainfall for 1976, 1995 and 2025   

Projections for Future Summers in Ireland 

Based on Met Éireann’s TRANSLATE climate projections, the number of heatwaves and high-temperature extremes in Ireland are set to increase as the century progresses. The extent of these changes will depend on future global greenhouse gas emissions, but all climate scenarios indicate continued warming. Summers are projected to experience increases in both maximum and minimum temperatures, along with a greater number of Summer Days. Warm nights (temperatures above 15 °C) are also expected to become more common, reducing the overnight cooling that currently provides relief during hot weather. 

Projections for average summer rainfall are far more uncertain than those associated with temperature changes. In this context ’uncertain’ means that the models providing future rainfall projections show a broader range of potential changes in the future. Projections for more extreme annual rainfall events (like maximum daily or  five-day precipitation) indicate a more consistent upward trend towards the end of the century. 

These changes have the potential to increase risks to public health, infrastructure, water resources, agriculture and ecosystems, highlighting the importance of adaptation measures to improve resilience to future heat extremes.