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Water and Air Temperature

The frequency and severity of hot weather and heatwaves in London is predicted to increase.

By the middle of this century, there is a 50% chance of summers as hot as it was in 2018, which was one of the warmest summer in the UK to date. London also generates its own microclimate, known as the Urban Heat Island, which can result in the centre of London being up to 10 degree C warmer than the rural areas around it.

The hotter summer in the UK means more people are likely to be drawn to the river to cool down.  Many new river users are unaware of the risks of the tidal Thames and with the higher river flow in the winter and lower water level in the summer can pose an even greater risk for recreational users, especially for swimmers and human-powered crafts. The PLA has been working alongside other organisations to make the river a safe place for all users. Find out more about the Tidal Thames Water Safety Forum here.

The hotter weather will not only increase the risk of heat exhaustion for the public and wildlife, but it can also exacerbate air and water quality. The PLA has been working on reducing the emissions of air pollutants from activities on the river through delivering the actions set out within our Air Quality Strategy since 2018

The river water temperature can be affected by the many factors, such as change in air temperature, river water level, and discharge and abstraction of river water by water companies. The increase in water temperature can resulted in a lower dissolved oxygen level, higher the chance of having a harmful algal bloom, and encourage invasive non-native species to colonised, which have negative impact on local ecology. The PLA works closely with water companies on their water management plans to minimise the disruptions that it would cause and the Environment Agency to monitor the water quality.