The bank holiday getaway was brought to a standstill for many motorists as soaring temperatures led to an increase in breakdowns.
Nearly 300 drivers of overheated vehicles called the AA to be rescued by 3pm on Friday, compared with around 150 on an average day.
Much of the UK basked in balmy temperatures, with Lossiemouth, Moray, reaching 29C (84F).
Many of the problems for motorists were caused by engines overheating due to a leak in the heating system or very low oil levels, according to the AA.
It also warned that poorly inflated tyres can quickly overheat.
The firm's patrol of the year, John Snowling, said: "The AA is already receiving higher numbers of calls for help than expected, tyre problems being the greatest cause.
"Patience may be needed because if the road is jammed, then the mobile mechanic coming to help you might well be stuck in the same traffic jam."
It is expected to be the busiest spring bank holiday weekend for traffic in four years, with the RAC estimated that 16.5 million leisure journeys will be taken between Friday and Monday.
This is 1.2 million more than last year and a rise of nearly 2.5 million on 2015.
Friday will be particularly busy as getaway traffic battles for space on the road with commuter vehicles, the RAC said.
Rod Dennis, RAC traffic spokesman, said: "The late Easter has meant there's been something of a bank holiday bonanza this year, with up to four days off in the space of just six weeks.
"But that's not stopping UK drivers from taking to the road for a leisure trip this coming weekend, especially as the weather at the start of the weekend at least is set to be dry, sunny and very warm for much of the country.
"We're expecting leisure journeys to reach a peak on bank holiday Monday as families set off for a half-term trip or take a day trip to the coast.
"But drivers should be warned that the roads are likely to see significant congestion on Friday as getaway traffic and everyday commuter traffic combines.
"We're expecting it to be bumper-to-bumper from Friday lunchtime onwards on some of the country's most popular routes."
Traffic information supplier Inrix warned that journeys via stretches of the M25 and M5 that normally take half an hour or less will last more than four times longer on Friday.
It also highlighted the M4 from Junction 2 to 13, the M6 from Junction 15 to 19 and the M60/M62 from Junction 8 to 20 as likely congestion hotspots.
Inrix chief economist Dr Graham Cookson said: "The combination of good weather, planned roadworks on major roads and the regular post-work getaway, will mean severe delays.
A number of rail routes in south-east England will be closed during the weekend as Network Rail continues to rebuild London Bridge and the surrounding tracks.
There will be no trains to or from Charing Cross, Waterloo East or London Bridge between Saturday and Monday, with services diverted to alternative stations in the capital.