The Thames Barrier

How the Thames Barrier works, and when it is scheduled to close.

The Thames Barrier is one of the largest movable flood barriers in the world. The Environment Agency runs and maintains the Thames Barrier as well as London’s other flood defences.

You can follow us on Twitter @AlanBarrierEA or read our blog posts. or like our Facebook page

Photograph of the Thames Barrier
The Thames Barrier

Forthcoming scheduled closures

The Environment Agency operates the Thames Barrier every month for maintenance and testing. Once a year, they also test the barrier at a high spring tide (normally September or October). They may begin closing and re-opening the gates up to an hour before the times listed below.

  • Wednesday 8 May 2019 9:35am to 12:05pm
  • Thursday 6 June 2019 9:25am to 11:55am
  • Thursday 4 July 2019 8:40am to 11:10am
  • Monday 19 August 2019 9:50am to 12:20pm
  • Sunday 29 September 2019 8:10am to 6:10pm
  • Thursday 17 October 2019 9:40am to 12:10pm

Very occasionally, the Environment Agency may need to change or cancel a closure at short notice. Please call the Thames Barrier to check: 020 8305 4188.

Forecasting closures

The Environment Agency receives information on potential tidal surges from weather satellites, oil rigs, weather ships and coastal stations. They can forecast dangerous conditions up to 36 hours in advance, and will close the barrier just after low tide, or about 4 hours before the peak of the incoming surge tide reaches the barrier.

They get information from a range of mathematical computer models that forecast expected sea and river levels. This is supplemented by data from the Met Office and real-time information provided by the UK National Tidegauge Network. This hydrological and meteorological data is fed into the control room every minute from a wide network of tide, river, pressure and wind gauges.

The decision to close, or not, is based on a combination of 3 major factors:

  • the height of the tide (usually a spring tide) measured at the Thames Estuary
  • the height of the tidal surge, which naturally accompanies each tide
  • the river flow entering the tidal Thames, measured as it passes over Teddington Weir

Find up-to-date data for river and sea levels at the Thames Estuary and Teddington Weir.

The barrier has no individual trigger level for closure. The closing process is guided by a mathematical matrix that considers the river flow, tide and surge at the time. The final decision for closure lies with the Thames Barrier Duty Controller.

How the Thames Barrier works

The Thames Barrier spans 520 metres across the River Thames near Woolwich, and it protects 125 square kilometres of central London from flooding caused by tidal surges. It has 10 steel gates that can be raised into position across the River Thames. When raised, the main gates stand as high as a 5-storey building and as wide as the opening of Tower Bridge. Each main gate weighs 3,300 tonnes.

The barrier is closed under storm surge conditions to protect London from flooding from the sea. It may also be closed during periods of high flow over Teddington Weir to reduce the risk of river flooding in some areas of west London including Richmond and Twickenham.

The Thames Barrier will then remain closed over high water until the water level downstream of the Thames Barrier has reduced to the same level as upstream. This is a managed process to provide for different circumstances, and takes about 5 hours. The Thames Barrier is then opened, allowing the water upstream to flow out to sea with the outward-bound tide.

You can watch a video that shows how the Thames Barrier works:

a video of how the Thames Barrier works

Thames Barrier closures

The Thames Barrier has been closed 184 times since it became operational in 1982 (correct as of March 2019). Of these closures, 97 were to protect against tidal flooding and 87 were to protect against combined tidal/fluvial flooding.

Thames Barrier closures since 1983.
Thames Barrier closures since 1983.

If you have an enquiry about the Thames Barrier, or would like to receive a project pack, email:

The future of the Thames Barrier

The Thames Estuary 2100 plan sets out how flood risk will be managed in the Thames estuary to the end of the century and beyond. It also recommends what actions the Environment Agency and others will need to take in the short term (the next 25 years), medium term (the following 15 years) and long term (to the end of the century).

The plan is based on current guidance on climate change, but is adaptable to changes in predictions for sea-level rise and climate change over the century.

More information can be found on the Thames Estuary 2100 page .

Visiting the Thames Barrier

New Thames Barrier cafe and information centre
New Thames Barrier cafe and information centre

The centre has an additional conference room and improved outdoor seating area, which allows the Environment Agency to offer more availability for group talks and conferences. This new room has additional cover for winter group talks. For more Information call 0208 305 4188.

The Environment Agency is currently upgrading the disabled lift, and the lift is out of service as of 4 September 2018 meaning there is restricted access to the Café. However, entrance to the Information Centre downstairs and toilets is still possible.

Please check opening times.

Date Open Last entrance to Information centre Closed
Thursday to Sunday 4 April to 21 July 2019 10:30am 4pm 4:30pm
Monday to Sunday 22 July to 25 August 2019 10:30 4pm 4:30pm
Thursday to Sunday 26 August to 27 October 2019 10:30am 4pm 4:30pm
Thursday to Sunday 27 August to 5 April 2020 11am 3pm 3:30pm

This webpage will be updated once the new lift is completed. The Environment Agency apologises for any inconvenience this may cause.

Group talks

Group talks available at the Thames Barrier Information Centre for all ages. Please see price list.

Please complete our booking form and email to

Refreshments, light lunches and afternoon teas available to pre-book with your group talks please enquire for further details and costs.

If you need any further information please call the Environment Agency on 0208 305 4188.

Published 25 April 2014
Last updated 17 April 2019 + show all updates
  1. Amendments made to opening times and group bookings section 17 April 2019.
  2. Updates to data and graphics made 27 March 2019.
  3. New graph and data uploaded 28 February 2019.
  4. Changes made 9 January 2019.
  5. New booking form uploaded 18 December 2018.
  6. New Booking Form uploaded 13 December 2018.
  7. Test closure cancelled for 13 December 2018.
  8. New opening times added on 20 November 2018.
  9. Update to closure dates made 29 October 2018.
  10. New information added 8 October 2018.
  11. Updates to information made 27 September 2018
  12. Information on disabled toilet added.
  13. Timings for the Thames Barrier annual closure added
  14. Additional test closure dates added 31 July 2018
  15. Disabled lift now working.
  16. Details on the opening of the new Cafe and Information Centre.
  17. New information for the Thames Barrier Information Center and Cafe.
  18. New dates for test closures added.
  19. Refurbishment of cafe delayed until June 2018.
  20. Numbers of closures updated.
  21. Two closures added to closure total.
  22. Correction to barrier closures.
  23. Information on the refurbishment of the Thames Barrier Information Centre and cafe.
  24. Data update 10 October 2017.
  25. Information about finding out if the Thames Barrier is closed via Floodline removed as service is no longer available.
  26. Thames Barrier Annual closure event information removed.
  27. New test closure dates, Cafe closing for refurbishment dates changed and warning to users of wheelchairs at the Annual Closure about access to river bank.
  28. Cafe opening at 9am on the Annual Closure day.
  29. Cafe opening times updated
  30. New information on Thames Barrier Annual Closure
  31. New times added for cafe and information centre.
  32. Taken out that the disabled lift is broken as now fixed.
  33. Information on disabled lift being out of order.
  34. New dates for Thames Barrier closures and group talks added
  35. Notice that the Information Centre will be closed between 30 October 2017 and 28 January 2018 for refurbishment.
  36. Updated opening times to cafe and Information Centre, new group talks dates added
  37. Tall ships dates and the 2017 Thames Barrier annual closure date added.
  38. Cafe opening times updated.
  39. Updated information on group talks
  40. New opening times added.
  41. New information added.
  42. November to March closure dates and information about the Open Day on 2nd October added.
  43. Updated closure dates.
  44. Special offers for Father's Day at the Information Centre.
  45. New group bookings added.
  46. New Thames Barrier Information Centre group talk dates, price list and booking form added.
  47. Notice of event at Information Centre.
  48. Annual closure times for 2016 added.
  49. Updated timetable for group talks.
  50. Visiting the Thames Barrier section has been updated.
  51. Details added about the annual closure.
  52. Details on the annual closure have been added.
  53. Updated closure times and group talk sessions.
  54. In summer 2015, the Information Centre is open 7 days a week during the school holidays.
  55. The test closure dates have been updated, and there is a new link to our blog posts.
  56. New information for group tours of the exhibition centre.
  57. New Barrier closure information.
  58. Updated planed closure dates
  59. Thames Barrier Information Centre prices from April 2015.
  60. Information on group talks added.
  61. Updated 'forecasting closures' section.
  62. Added new closure dates for 2015.
  63. First published.