A wildfire warning is in place across much of the country because of warm and dry conditions.
The Met Office put most of England, including London, under an amber wildfire alert that will extend into Northern Ireland and southern Scotland on Wednesday.
It came as spring brought warmer temperatures, which are expected to peak at 22C (71F)on Friday.
Londoners were urged not to have barbecues in open spaces or on balconies and to throw all of their rubbish away to avoid creating a fire hazard.
“With strong winds and ongoing dry/warm weather this brings a continued likelihood for wildfire conditions through the period,” said Kathryn Chalk, a meteorologist at the Met Office.
“It’s a large warning, covering most of England. We can’t be specific on locations because of the nature of wildfires though, and best to stick with the weather conditions with the dry air, breezy and warm conditions.”
England had its sunniest March on record last month, as well as its sixth driest, as persistent high pressure brought long spells of clear weather.
Scotland and Northern Ireland also saw an above-average amount of sunshine, at 20 per cent and 13 per cent respectively, though neither nation came close to record levels.
The UK had just 43 per cent of its average rainfall for March, with southern England particularly dry.
London last had wildfires during the heatwave of 2022, during one of the driest periods on record for the country. The fires destroyed 41 properties and led to the biggest demand on the Fire Service since the Second World War.
In 2020, the Met Office issued an amber wildfire warning as early as March for most of Sussex.
The London Fire Brigade warned that a particularly dry start to the year was increasing the threat of fires, despite temperatures not being dramatically high.
Paul McCourt, London Fire Brigade’s assistant commissioner, said: “We want everyone to enjoy the sunshine, but we urge people to take the necessary precautions to stay safe and help prevent a grass fire from starting.
“Recent events in Los Angeles and South Korea have demonstrated how rapidly fires can spread outdoors, even when temperatures are not at their highest.”
A 10-day fire that killed 30 people in South Korea last week may have been started by a man performing an ancestral burial ritual, authorities there have said.
The Met Office said showers moving into the far South West would bring some relief to that part of the country, while drier weather would continue elsewhere into Friday and Saturday.