Autumn leaves set to dazzle UK after warm summer

Autumn leaf colors across the United Kingdom are forecast to be unusually vivid after a warm and sunny summer, Forestry England said. The agency notes that trees stored more sugars in their leaves, providing fuel for brighter displays. Andrew Smith, director of Westonbirt, The National Arboretum, said, "We've had a very warm and sunny summer, and that helps trees build up the sugars in their leaves that create those amazing autumn colours...and we're expecting a really beautiful display this year."

Experts explain that as nights lengthen and daytime temperatures fall, the production of the green pigment chlorophyll slows, revealing the underlying yellows, oranges and reds. The record-breaking warmth of the summer meant trees produced more sugars in their leaves, and higher sugar concentrations can drive the production of anthocyanin, which deepens red tones. Forestry England cautions that the exact display will vary by species and season conditions.

However, not all trees change colour at the same time. Kevin Martin, head of tree collections at Kew Gardens, said some species have already turned and shed their leaves, a phenomenon described as a 'false autumn.'

With rainfall returning in recent weeks, Kew Gardens reports some trees—such as horse chestnut—have started to regrow leaves temporarily before the usual autumn change. The effect underscores how drought and then wet spells can disrupt the sequencing of colour change.

Regional timing will also vary. In southern England, colour change is expected to begin from mid-September. At Kew, Kevin Martin said there will be a good overlap with many trees changing colour from mid-to-late October. The American ash is singled out as a standout, with leaves turning golden yellow before progressing to purples and deep red.

Across central parts of the UK, peak colours are anticipated from late September to mid-October, while northern areas, with cooler and wetter conditions, may see colours linger into November. Forestry England noted that if warm days persist and nights cool and dry in September, this could yield one of the most flamboyant autumn displays in recent years.

Because different species respond at different rates and conditions vary by region, observers should expect a staggered spectacle across the country and plan visits accordingly.