Monday itself is predicted to be the busiest day, with 5 million leisure trips -- up nearly 1 million (22%) on 2016. Saturday also looks to be a popular day for travelling by road, with 4.4 million separate journeys due to take place.
RAC traffic spokesman Rod Dennis commented: "While summer appears to have taken a leave of absence for many of us, our figures suggest drivers are undeterred and are still keen to make the most of the long weekend to spend time with friends and family in the UK.
"We recommend motorists wanting to beat the queues travel outside peak times -- so avoid Friday afternoon and evening if you can and try to get away in good time if you are planning a day trip on Monday, or face a long journey home at the end of a summer holiday."
To help ease the flow of traffic, Highways England is lifting around 450 miles of roadworks on the nation's motorways and major A-roads -- and is urging motorists to make sure their vehicles are ready for the journey.
Highways England operations director, Nick Harris, said: "We're lifting more than 98% of roadworks this bank holiday to help people get where they need to as safely and quickly as possible. If you're driving out to enjoy the late summer bank holiday, make sure you take a few vital minutes to check your vehicle, especially if you haven't done so for a while."
Last year more than 20 motorists broke down each day during July and August because they had run out of fuel. Many other breakdowns are caused by simple mechanical problems which could be avoided by carrying out some basic checks before you set off.
"It only takes a single breakdown on a congested road to cause real disruption, so we also advise drivers to complete some quick, basic checks that can reduce the chances of their vehicle being the culprit," said the RAC's Rod Dennis. "Make sure your tyres are in good condition and are properly inflated, and check your oil, coolant and screenwash are all at the right levels. Don't forget to fully charge a few mobile phones before you set out too so you can reach help should you need it."
Are you planning a bank holiday getaway this weekend?