South-easterly winds are expected to draw warm air from Europe towards the UK from Friday, bringing rising temperatures along with dry and settled weather.
Recording-breaking temperatures could be felt in the South East on Monday.
The highest temperature for the late August bank holiday weekend is 31.5C (88.7F) at Heathrow Airport in 2001.
Met Office chief meteorologist Steve Willington said: “We’ve had a fairly wet and windy August so far, however that’s going to change this weekend as we see high temperatures, sunshine and light winds return.
“On Saturday and Sunday there’ll be plenty of sunshine across the country with temperatures reaching into the mid-20s for many – it’ll be warmest in southeastern parts where 30C (86F) is possible.
“By Bank Holiday Monday itself temperatures will rise further with around 33C possible in the South East – which would set a new record for the coming bank holiday weekend.”
The sunny spell could set a swathe of new records around the country, with the current hottest late summer bank holiday in Wales standing at 27.3C (81.1F) at Velindre, Powys, in 2013.
The record for Northern Ireland is 27C (80.6F) recorded in Knockaraven, County Fermanagh in 2003.
Monday is not a bank holiday in Scotland.
Last month the UK felt its highest temperature ever recorded – with the mercury reaching 38.7C (101.7F) at Cambridge University Botanic Garden on July 25.
That exceeded the previous record of 38.5C (101.3F) set in Faversham, Kent, in August 2003.
RAC spokesman Rod Dennis said with summer returning in time for the weekend, those going out for day trips and short breaks should check their vehicle before setting out.
He said: “Tyre pressure and tread, as well as oil and coolant levels, should all be looked at and doing so can really cut the chances of breaking down.”
HM Coastguard has urged those planning a trip to the coast at the weekend to follow their safety tips.
Bev Allen, maritime operations controller, said: “Warm weather is forecast for much of the country this weekend and whatever the weather, the bank holiday is when many people quite rightly want to make the most of our wonderful coastline and beaches.”
The coastguard has issued the following advice:
- Do not jump into the water from piers, rocks, cliffs or other structures that can lead to fatal incidents.
- Look out for lifeguards, and choose beaches where lifeguards are on duty and take note of their advice, especially when you want to enjoy a swim.
- Swim parallel to the shore and avoid most harbours and fast-flowing water.
- Don’t get carried away: Inflatables are not suitable for use in the sea and they can go from fun to potentially deadly in minutes, so best save them for swimming pools. Tide conditions, the wind and any changes in the weather can very quickly sweep them out to sea and beyond safe depths.