Europe's biggest street festival - celebrating Caribbean culture, food and music - opened at 9am with the start of the procession as forecasters predicted temperatures of up to 26C.
Thousands more were expected to gather on the streets around the carnival route where dozens of sound systems had been set up.
By 11am thousands had already lined the streets of Notting Hill to see the carnival procession.
Onlookers included people from all of the UK.
Monique Piret, 36, went to see the parade with a friend.