Recent summers have shown how quickly extreme heat can affect daily life in the UK. According to BBC Weather, July 2026 has seen parts of southern England approach two weeks of heatwave conditions, while the UK recorded its longest spell of consecutive 30°C days since 2006. In towns and cities, that heat is amplified by the urban heat island effect.

According to the Met Office State of the UK Climate report, UK heatwaves are becoming more frequent, longer-lasting and intense. With the UK now 1.33°C warmer on average than it was during 1961–1990, the shade and cooling provided by trees can make a real difference to how safe and liveable our cities feel.

What's an Urban Heat Island?

Cities become urban heat islands when they are warmer than surrounding rural areas. Roads, pavements and buildings absorb and store heat during the day, then release it slowly after sunset. Traffic, air conditioning units and other human activity can add to the problem, while limited tree cover and green space reduce natural cooling.

The vast majority of us live in towns and cities: over 80% and rising in the UK. With more people living in urban areas, extreme heat is becoming a growing public health and climate challenge. Urban heat can worsen air quality, increase heat-related illness and make everyday journeys, homes and workplaces harder to cope with. As heatwaves become a regular feature of urban life, nature-based solutions are becoming increasingly important. One of the most effective — and overlooked — is trees.

Since 1993, Trees for Cities has engaged more than 260,000 people to plant and care for 2 million trees across 100 towns and cities, helping communities create greener, cooler and more resilient places to live.

How do trees cool cities?

Trees cool cities in three key ways: by providing shade, releasing water vapour through transpiration, and reducing the amount of heat absorbed by hard surfaces. They make streets, schools, parks and public spaces more comfortable during periods of extreme heat. Heat maps from Friends of the Earth show that across five major English cities, areas with more trees and green spaces are up to 5°C cooler. The Food and Agriculture Organisation of the United Nations states that strategically planted urban trees can cool the air by up to 8°C.

But these benefits are not felt equally. Some neighbourhoods have far less tree cover than others, leaving communities more exposed to extreme heat. That is why investment in urban greening must prioritise the places where trees can make the biggest difference.

Protecting trees for future generations

At Trees for Cities, we know that it’s just as critical to care for urban trees as it is to plant them. It can take between 25 and 50 years for a tree to reach the right level of maturity to unlock all of its benefits, so watering and tending to growing trees will help them thrive for the long term. During hot, dry spells, it's especially vital to water urban trees when rainfall is in short supply — and everyone can play a part.

Planting a cooler future

The need for urban trees is only growing. As towns and cities face hotter summers and increasing climate pressures, we're working to grow a movement for urban trees and tree equity so that everyone can benefit from cooler, greener and healthier neighbourhoods.

Help us plant and protect urban trees where they are needed most. Your support helps create cooler, greener, healthier places to live — bringing shade, cleaner air and climate resilience to communities across the UK.