Around a hundred firefighters are battling a wildfire in Wales as more than 70 blazes have broken out across the UK.
A statement issued by Dyfed-Powys Police said around 100 members of staff from Mid and West Wales Fire and Rescue Service were at the scene in Milford Haven.
It comes as South Wales Fire and Rescue Service reveal crews saw a shocking rise in wildfires this weekend as they were dispatched to almost 70 deliberate grass fires from Friday to Sunday.
A spokesperson said: "At approximately 2pm this afternoon (Sunday August 14) Mid and West Wales Fire and Rescue Service was called to the scene of a large waste site fire at a unit in Waterston Industrial Estate.
"A large storage unit has been destroyed by the fire, which spread to an adjacent waste recycling centre. Crews are working to extinguish the fire at both locations and mitigate further spread.
"Significant smoke is billowing from the scene of the fire, and residents in the Johnston, Milford Haven, Pembroke Dock, and Neyland areas as well as the other side of the estuary are advised to keep windows and doors closed, and remain indoors until further notice."
A tweet from Llandod Fire this evening said "Night-fall over Newgale… still a nice orange glow"
"Could be a long night, long way from home..! #oncall"
The tweet was posted with a dramatic image showing vivid orange flames and white smoke billowing up from the hills around Pembroke.
A Public Health Wales spokesperson added: “Motorists who have to travel through the smoke should keep windows closed, turn off air conditioning and keep their air vents closed".
Councillor of Mountain Ash West and Labour leader at Rhondda Cynon Taf Council, Andrew Morgan has confirmed Rhigos Mountain Road in Treherbert, near the scene of the fire, will need to stay closed.
In a brief statement on Twitter, he wrote: "Update - Rhigos Mountain Road: Council Officers attended this evening and assessed road will need to stay closed Engineers will attend on Monday, subject to safety works being carried out and proactive barriers put in place, road MAY reopen under temporary traffic lights in few days."
A statement from South Wales Fire and Rescue Service said that, among the 70 blazes the service has faced, included large fires in Garn Wen in Maesteg, Fox Hill in Rhiwderin, Trealaw area of Tonypandy and Penrhys in Ferndale.
The statement said: "The majority of these fires have required the attendance of multiple appliances, use of critical equipment and the movement of resources.
"This usually includes multiple fire engines, specialist wildfire vehicles and a helicopter at the scene working in partnership with police colleagues, Natural Resources Wales and the local authority.
"Deliberate fires are unacceptable at any time, but during a time of national crisis emergency service resources are critical in protecting the public.
"Wildfires are extremely dangerous and can spread extremely quickly putting lives in danger, causing significant damage to property and the environment including causing harm to wildlife.
"The fires also give off thick swathes of smoke which can increase the risk to the elderly and vulnerable people with medical conditions. Healthcare professionals have highlighted the dangers of smoke caused by grass fires to COVID-19 sufferers who may be living nearby.
"To tackle this problem we are working with our partners across Wales as part of Operation Dawns Glaw, a taskforce set up to reduce the number of deliberate fires. While we remain committed to delivering an effective and efficient emergency response across South Wales, these fires are a drain emergency service resources placing unnecessary risk on lives.
"We would urge anyone who has information on suspected deliberate fires, or who sees anything suspicious to contact 101, or call Crimestoppers anonymously on 0800 555 111.
"If you see a fire, or anyone starting a fire, please call 999 immediately."
The hot weather has also led to several wildfires erupting across England, with blazes breaking out in Yorkshire, Northamptonshire, Essex and Devon.
Temperatures reached 34C on Sunday as the UK braces for three days of rain and yellow weather warnings. The Met Office said Charlwood, in Surrey, recorded the highest temperature with 34.1C.
The fires come as a search is also under way for a man in the River Thames in west London after he was reported getting into difficulty in the water.
The Metropolitan Police said a "multi-agency response" was in operation after they received reports of the man in the water at Hampton Court at 4.12pm.
A spokesman for Scotland Yard said: "Officers from the Met and Surrey Police, the National Police Air Service, as well as the London Fire Brigade, London Ambulance Service and RNLI, began searching the river.
"However despite the best efforts of everyone involved the man has not been found. Efforts to inform all of his next of kin are ongoing while work to recover the man continues."
In Scotland and Northern Ireland, a yellow warning for thunderstorms was in place from 9am on Sunday as the north experiences a sweep of heavy rain for the next two days.
The severe weather began to impact stores as customers were evacuated from a Tesco supermarket in Inverness when water poured in through the ceiling.
Videos on social media showed tiles on the ceiling falling to the floor and water pouring in, covering most of the floor in the supermarket on Sunday.
From Monday, the warning extends to Wales and England.
The forecaster has warned of flash flooding, thunder, lightning and power cuts as showers beat down across the nations.
The warning remains in place in Scotland and Northern Ireland until 11.59pm on Monday and 11.59pm for all of England and Wales on Tuesday.
The south west and south east of England also face a third day of yellow warnings on Wednesday until 11.59pm, as the rain eases off elsewhere.
An official drought was declared in eight areas of England on Friday by the National Drought Group (NDG), which comprises representatives from the Government, water companies, the Environment Agency (EA) and others.
Three water companies - Welsh Water, Southern Water, and South East Water - have all imposed hosepipe bans, while Yorkshire Water has announced a ban will start on August 26 and Thames Water is planning one in the coming weeks.
Mr Stroud said that despite the forecast of intense showers over the next few days, it is unlikely to help the drought.
"It will help a little but to be honest really, it's almost the wrong sort of rain," he said. "What we're likely to see is some heavy, intense downpours. With the ground baked so dry, it's very difficult for the ground to actually absorb the water very quickly.
"So what tends to happen in these circumstances is the water runs off and we can potentially get some surface run-off issues, so some flash floods."
