In Pictures: England soaks up more hot weather
Blue skies and hot sunshine have continued into the working week after temperatures peaked at 32C (91F) in London, beating Sunday's hot weather.
Overnight, it was hotter in parts of the UK than it was in Istanbul during the day.
The mercury hit 24C (75C) at midnight at London City Airport - hotter than in the Turkish city where temperatures stayed below 21C (70F).
Temperatures had reached 30.2C (86.36F) in south-west London at the weekend.
Monday's top temperature was recorded at RAF Northolt in west London.
Forecasters have anticipated highs of 33C (91.4F) during the days to come.
In the West Midlands, working dogs at Stourbridge fire station needed to cool down.
Firefighters tweeted pictures of the dogs jumping for water from hosepipes and wrote: "@WestMidsFire even the fire dogs feeling the heat @Stourbridgefire white Watch"
In Lancashire, roads were seen melting in the high temperatures.
The Hesketh Bank and Tarleton Community Group wrote on Facebook: "If your [sic] thinking of avoiding Hesketh Lane I would think twice about using Taylors Meanygate unless you want tar all over your car. The road has melted."
Surrey Police said there had also been an incident of a road melting in Guildford, where spilt oil had "melted into the tarmac due to the heat".
BBC Weather Watchers captured the skies at sunset on Sunday, and as Worcestershire woke to glorious blue skies on Monday.
The high temperatures have been attributed to warm air originating from the tropical Atlantic.
In some spots, the strength of the UV has been recorded as being as high as that in Cyprus and Gibraltar.
And BBC Sussex took its Big Bus Tour to seaside resort Bognor Regis.
The Met Office said the first half of the week would see temperatures in the high 20s or low 30s for many across England and Wales, but there was some cloud and drizzle to the far north of Scotland.
Temperatures are expected to return nearer to average over eastern parts of the UK on Tuesday, but the fine, very warm and sometimes humid conditions in the south will continue until Thursday.
The Met Office has issued a level three amber heatwave warning from Monday to Thursday, "meaning there is a 90% probability of heatwave conditions", according to its website.
It means health and social workers should ensure high risk groups, including the elderly, children and those with medical conditions, are kept cool and hydrated.
Public Health England has also issued hot weather advice, with people urged to keep an eye on older people and young children as well as those at risk with heart and lung conditions.
Tips include to:
- Close curtains to keep indoor spaces cooler
- Drink plenty of water
- Walk in the shade
- Apply sunscreen and wear a hat
- Avoid physical exertion in the hottest parts of the day
- Carry water when travelling
People are also urged not to leave anyone in a closed, parked vehicle, particularly young children and animals.