Dry Spell Brings Early Autumn Colours to Irish Trees

Leaves in parts of Ireland are beginning to take on their autumn colours ahead of schedule, with the shift from green to gold and brown accelerated by recent drier-than-average weather.

The first signs of seasonal change usually appear in mid to late September, but reports from several counties suggest the process has started earlier this year.

Rainfall has been below the long-term average in many areas in recent weeks, particularly in the east and midlands, leaving soils drier than normal for August.

In the past week alone, Dublin Airport’s Casement station recorded just 0.2mm of rainfall during the past week, while Dublin Airport has recorded 4.3mm of rainfall for the month to date. Even the normally soggy southwest has been drier than normal. Valentia has recorded only 29% of its average August rainfall up to today.

Trees respond to water stress by conserving resources, which can trigger the early breakdown of chlorophyll, the green pigment in leaves. This reveals the underlying yellow and orange carotenoids, while some species produce red anthocyanins as a protective measure. Prolonged dryness can cause leaves to bypass these colours entirely, turning brown and falling prematurely.

Early browning is often a sign that a tree is prioritising survival over seasonal display. When under drought stress, a tree reduces water loss by shutting down photosynthesis earlier than usual, which can bring on an early autumn.

Native species such as birch, rowan and hazel tend to show the effects first, while deeper-rooted trees like oak can tolerate dry spells for longer. Urban trees, which often contend with compacted soils and restricted root space, may also be among the first to change colour.

With a return to more typical August showers forecast in the coming days, the pace of colour change may slow. But for now, the first hints of autumn are already visible on roadsides, in hedgerows, gardens, and across public spaces nationwide.