Passengers faced severe disruptions during the morning rush-hour as four Tube lines were hit by signal failures.
Victoria Line was suspended between Victoria and Brixton while there was no service between Baker Street and Aldgate on the Metropolitan Line.
There were also severe delays on the Circle and Hammersmith and City Line.
Transport for London (TfL) said the failures were caused by bad weather overnight. Services on these lines have now returned to normal.
Mainline train delays
A signal failure at Seven Sisters affected services on the Victoria Line while another signal failure at Euston Square hit the Metropolitan, Circle and Hammersmith and City Lines.
A TfL spokesman said: "There are delays on the Victoria, Metropolitan and Hammersmith & City lines this morning as a result of signal failures caused by last night's heavy weather.
"Our engineers have now resolved these problems and services are returning to normal."
An electrical supply problem also caused delays on the First Capital Connect and Southeastern trains.
Passengers faced delays of up to 30 minutes between Blackfriars and St Pancras stations following the electrical problem in the Kentish Town area, north-west London.