The risk of how severe fires could become across parts of England and Wales has been raised to "exceptional" - the highest it can be - as a four-day amber weather warning comes into force.
The top level on the fire severity index applies to much of southern England, and reaches as far west as Abergavenny in Wales, for this coming Sunday.
The index is an assessment of how severe a fire could become if one were to start, not the risk of fires occurring.
The Met Office has issued an amber heat warning running between Thursday and Sunday, and temperatures between those days could peak at 36C.
South East, Southern and Welsh Water have all announced hosepipe bans for customers in areas they supply.
There have also been repeated warnings about the impact on agriculture, rivers and wildlife.
Met Office meteorologist Marco Petagna said: "The risk [of fires] is very high across much of central, southern and eastern England.
"Going into Friday and the weekend, it starts to increase further, going into the highest category of exceptional risk."
What are the rules on hosepipe bans?
Worst summer for fires in three decades
Mark Hardingham, the chairman of the National Fire Chiefs Council, told The Telegraph he "can't remember a summer like this" in his entire 32-year career.
"We're not going to see temperatures as hot as we saw three weeks ago, but that doesn't matter because the ground couldn't get any drier than it already is," he said.
There is also a heat health alert in place from the UK Health Security Agency, with experts advising people to look out for those who are older or with existing health conditions, as well as young children.
The latest analysis from the UK Centre for Ecology and Hydrology has warned low or even exceptionally low river flows and groundwater levels are likely to continue for the next three months in southern England and Wales.
Mr Petagna said rain could be on the horizon early next week.
"There are signs that we could get some rain next week, but details at the moment are uncertain," he said.
He added the UK needs "a few weeks" of light rain to water the ground.
"What we really need is a few weeks of light rain to soak into the ground," he said.
"Thunderstorms are more likely to cause some flooding issues because the ground is hard, the water can't sink in."