Forecasters say around 50 to 100mm of rain is expected to fall in parts of the country from Friday to Sunday.
It comes as thousands of pubs, bars and restaurants in England prepare to reopen on Saturday, after months of closures to slow the spread of Covid-19.
As Brits prepare to head out to their favourite local, strong winds and rain will move in from the west during the morning, becoming heavier into the day.
The wet weather means indoor venues could struggle to implement social distancing measures, with people ditching beer gardens and outdoor spaces to move inside out of the rain.
Covid-19 infection rates are believed to be higher in inside spaces.
Met Office spokesperson Craig Snell said that although the rain will lessen during the evening, low cloud and drizzly conditions will continue through to Sunday.
He said: "The changeable unsettled conditions that we have had in the last few days is going to continue into the weekend.
"Saturday itself will be quite cloudy with showers beginning in the west during the morning before moving across to the east.
“Some areas in the east could become particularly heavy for an hour or two in the mid-morning to early afternoon.
“Pushing in after that will be a spell of drizzly downpours and some low cloud which will hang over the UK for the rest of the day.”
Mr Snell said that across Friday, Saturday and Sunday parts of the country could see between 50-100mm of rain.
He also said the best of the sunshine on Saturday will be across the Pennines and Snowdonia in Wales.
"Despite the clouds, it will still be quite humid" Mr Snell said, adding that maximum temperatures of 24C in London and the South East, while central and northern parts of England will reach highs of 20C.
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A spokesman from JD Wetherspoon, which plans to reopen all 750 of its venues on Saturday, said: “The weather is out of our control, but our pubs tend to be three times larger than others so we are not worried about people being inside our venues.
“We can’t predict what the weather will be like in England, but we have faith that our customers and staff will be as safe as possible.”
A spokesperson for Stonegate Pubs, which owns The Slug and Lettuce chain, said: “Throughout our pubs and bars, we are implementing clear, safe socialising measures both inside and across our outside spaces.
“We are encouraging customers to pre-book and all bookings work on a time-limit which enables us to manage capacity and customer expectation.
“Should the weather be inclement, we will work with our customers on a common-sense approach, accommodating where we can those that have had to move from outside areas.
“Most customers are likely to check the weather and be prepared for the expected short spells of rain or drizzle.”