Current Climate and Projected Climate Changes in Ireland (summary of Chapter 3)

Ireland’s weather is known for being mild and wet, but in recent years has experienced record-breaking storms like Storm Éowyn (2025) as well as increasingly severe and frequent flooding.

Extreme weather events are becoming more frequent, and in some instances, more destructive. This is part of a long-term trend driven by climate change and is already affecting how our transport system functions, from flooded roads and damaged bridges to delayed flights and flooded train tracks.

No one can predict the future with complete certainty. To understand what lies ahead, scientists use climate models to simulate how Ireland’s climate might change under different global emissions pathways. T-SAP II follows the approach used in the National Climate Change Risk Assessment and considers two possible scenarios:

• RCP4.5 – a moderate scenario where global greenhouse gas emissions are significantly reduced over time. This is broadly associated with a +2°C rise in global temperatures by 2100, measured from the beginning of the century
• RCP8.5 – a high-emissions scenario representing a “business-as-usual” future with limited climate action in which emissions continue to rise throughout the century. This is associated with a +4°C rise in global temperatures by 2100, measured from the beginning of the century

For each of these scenarios, the plan examines changes over three key timeframes:

• 2030s – near term
• 2050s – mid-century
• 2100 – long term

This approach allows planners to assess a range of possible futures, from a more manageable level of warming to more extreme conditions and make decisions that are resilient across different outcomes.

Projections from Met Éireann and other relevant sources show that, under a high emissions scenario (RCP8.5), by 2100 we could see:

• summer temperatures rising by up to 2.6°C
• heatwaves becoming more frequent, from rare events to several per decade
• frost days reducing by over 80%, especially in eastern and higher areas
• winter rainfall increasing by over 20%, raising the risk of flooding
• summer rainfall decreasing by up to 7%, leading to droughts and risks to road surfaces
• sea levels rising by up to 0.7 metres in Dublin
• severe storms happening up to 3.6 times more often by 2080

Read more about Ireland’s climate and how it is changing in Chapter 3 of the plan