All lines have now reopened, but Great Western Railway has warned there may be delays or cancellations while services return to normal.
Trains will be delayed between Paddington and Reading until approximately 3pm.
The line between Maidenhead and Taplow is currently blocked due to a signalling problem.
High speed services between London Paddington and Reading will be diverted, causing delays of up to 15 minutes, and trains will be unable to stop at Maidenhead or Taplow.
National Rail is advising passengers wishing to stop at Maidenhead to travel to Reading and connect on a return service to the station.
More to follow.
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The Met Office has issued a yellow alert for Windsor and Maidenhead, Slough and Wokingham, warning that rain moving eastwards across the south of the country may turn to snow in some places.