Flood alert for Upper River Colne and Radlett Brook
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High river levels overnight may lead to flooding.
Flooding is possible on 27 August 2026 Due to forecast heavy rain and storms overnight.
It is unclear where the heaviest rain will fall. Locations most affected will be low lying land, roads and riverside gardens. Flooding from surface water, where water gathers and flows off road surfaces, could also occur. We expect river levels in areas that receive the heaviest rain to respond by rising quickly. Further heavy rain and thunderstorms are forecast during the day on Thursday 27 August and into Friday 28th August.
We are closely monitoring the situation and we are prepared to issue flood warnings if required.
Take care and avoid walking, cycling or driving through flood water and avoid using low lying footpaths and any bridges near watercourses.
This message will be updated by 10:00AM on 27 August 2026 or as the situation changes.
Flood alert area: The Upper River Colne and Radlett Brook at Colney Heath, London Colney, Borehamwood and Radlett.
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