And the number of incidents the fire service had to respond to was also the highest for two years in 2019/20.
It comes as callouts across England for firefighters to attend water rescues and flooding incidents reached their highest levels for seven years.
While firefighters have warned the UK is in “real danger” as climate change sees the nation threatened by “similar floods to those in Europe when dozens of people lost their lives”.
Data analysed by NationalWorld, LondonWorld’s sister title, revealed that rescues and casualty levels across England were at their highest for at least a decade.
It comes as delegates at the COP26 climate conference in Glasgow, Scotland, are set to discuss how to help communities prepare for “the worst impacts of climate change” – with “adaptation and resilience” a key theme of the make-or-break gathering of nations.
A Home Office database of non-fire incidents attended by fire and rescue services in London reveals crews were called to the scene of 6,959 floods or water rescues in 2019/20 – the highest since 2017/18.
The data also shows firefighters made rescues at 21 of the incidents in London – the joint highest number since records began in 2010/11.
At least one casualty or fatality was recorded at 26 incidents.
Figures for England stood at crews called to 16,710 floods or water rescues in 2019/20, hitting a seven-year high not matched since 2012/13.
The figures exclude rescues from settings where swimmers may have gotten into difficulty, such as lakes, rivers, beaches or the sea.
Instead, the data covers the types of incidents that could be affected by extreme weather – in homes, gardens and other buildings or on roads, pavements and from vehicles.
Earlier this year NationalWorld revealed how councils in England had spent £1.7 billion on flood and coastal erosion defences over the last decade, with real terms spending on floods rising by 176% and on coastal defences by 59%.
The Fire Brigades Union (FBU) said the rescue data “confirms what firefighters already know – as the effects of climate change increase, flooding is getting worse”.
FBU general secretary Matt Wrack, said the nation is in “real danger” this winter of “similar scenes to those in Europe this summer, when dozens of people lost their lives to floods”.
He said: “Fire and rescue will be a key part of adapting to this element of climate change. Yet at the moment the Government isn’t even providing statutory funding specifically for flooding.
“That needs to change. We’ve heard stories of firefighters left without dry suits, or left exposed to microbes in flood waters due to suits not being adequately decontaminated.
“Firefighters being left in a position where they can’t properly fight floods is a danger to them and to the public.
“We also need more sufficient staff to deal with the increases in flooding. Restoring the 20% of firefighters lost since 2010 would be a good place to start.”
The Home Office was approached for comment.