Pubs and bars are expecting a busy three days starting on Friday, as weather forecasters predicted a mini-heatwave for the weekend. Officers also fear of a surge illegal raves and house parties.
Groups of up to 30 people will still be allowed to socialise legally this weekend. But that drops to six on Monday.
Front-line officers are concerned the public may “go crazy” with dozens already posting on social media plans to host parties ahead of the new measures.
This weekend also sees the start of the new Premier League season with Arsenal, Crystal Palace, Fulham, Tottenham and West Ham in action. Relegated Watford play in the Championship.
While matches are being played behind closed doors, there is concern that fans will flock to pubs showing them on screens.
The Met has dealt with more than 1,000 unlicensed music events since June. More than 134 were held in the capital over the Bank Holiday weekend in August.
Sean Williams, 34, was fatally stabbed in the neck trying to break up a fight at an event attended by over 100 revellers in Catford at around 5.30am on Sunday.
Organisers are ignoring face fines of £10,000 under the coronavirus regulations.
Met Commander Ade Adelekan said: “Coronavirus still represents a real and deadly threat.
“Restrictions on gatherings are still in place and police will continue to engage within their communities, taking enforcement action as a last resort where necessary.”
Martin Hewitt, chair of the National Police Chiefs’ Council, added: “As we start to see a rise in infections it is vitally important that we all follow the regulations and restrictions in place to prevent the spread of Coronavirus.
“Everyone has a role to play limiting the outbreak by following the regulations, including those about gatherings which are now limited to six people both indoors and outside.
“Officers will continue to be out in communities – engaging, explaining and encouraging people to act responsibly. We will take enforcement action where necessary.”
It came as Londoners were forecast a final taste of summer with temperatures set to hit 30C in a mini-heatwave this weekend.
The Met Office said a “bulge in jet stream” would spark the mini-heatwave in London and the south east as warm air moves into Britain from Europe. It will last from Sunday to Thursday.