Temperatures could reach up to 18C on Bank Holiday Monday in the capital.
However, Saturday was predicted to be the perfect time to dust off your barbecue as temperatures could hit the late teens before dipping on Sunday.
Sarah Kent, a meteorologist at the Met Office, said “mixed weather” is forecast overall for the long weekend.
She added: “Saturday (April 30) will be a chilly start to the day with a mixture of sunny spells and occasionally cloudy skies. But it will be staying dry and temperature-wise it could hit 17C - so actually not that bad.
“There will be a cloudy start to Sunday (May 1) with probable spells of light rain which will get lighter and patchier during the afternoon but will hang about until dark. Temperatures will be more like 13C or in the low teens.
“So if you are planning a BBQ Saturday would be better I would say.”
She added: “It’s a mixed day on bank holiday Monday (May 2) so you should keep the brolly to hand just in case.
“There will be only light outbreaks of rain but it won’t stay completely dry but temperatures will rise again to 18C.
“Overall it’s a mixed bank holiday but we’ve had worse. At least we start the bank holiday with a dry and sunny note.
“If you want to have a BBQ on the Sunday - I would say just go for it in the rain.”
The capital is due for average May weather overall with fewer days of rain expected and temperatures ranging between 15C and 21C.
It will honour Her Majesty with an extended bank holiday week.
The second bank holiday in May has been shifted to form the four-day Jubilee weekend.