The Met Office said that temperatures are expected to rise over the weekend, with the mercury hitting the high teens by Monday.
It comes after a chilly but sunny start to the week as pub gardens, gyms and non-essential shops began to reopen after lockdown.
The Met Office’s senior press officer Grahame Madge said: “A signal for more settled weather is when an area of high pressure begins to develop. But it all rests on where the centre of the high pressure falls. If it's Norway then as air circulates we will get air from the south which is warmer.
“If it lands on Ireland the chillier air will circulate from the north and west. There is currently a bit of uncertainty about where it will form.
“We would say the indication is it's likely to be around average for April but it's likely the temperature would pick up. That spring sunshine is starting to punch through the atmosphere and will get hotter through the day.
“Mid 16C, possibly 17C is in the realms of possibility for London.”
Friday is due for a cold and sunny start with some fair weather cloud then likely to develop. But will likely stay dry, with warm sunny spells as the mercury hits 13C.
For the rest of the weekend, dry sunny spells are expected in the capital. But it will remain cold overnight, with frost and fog patches.