Temperatures in Hertfordshire are set to peak at today, with disruption expected at schools, businesses, roads and railways throughout the county.

A Met Office red warning for "extreme heat" is in place over a large part of England today (Monday, July 18), including Hertfordshire.

The Met Office said the temperatures are "exceptional", while the UK Health Security Agency is urging members of the public to look out for relatives.

A statement by weather forecasters reads: "An exceptional hot spell on Monday and Tuesday leading to widespread impacts on people and infrastructure.

"Population-wide adverse health effects experienced, not limited to those most vulnerable to extreme heat, leading to serious illness or danger to life.

"Substantial changes in working practices and daily routines will be required."

%image(14509740, type="article-full", alt="A woman shields herself from the sun in central London on July 17")

Dr Agostinho Sousa, the UKHSA's head of extreme events, said: "Temperatures in England are likely to reach record levels, and it’s important we all know how to stay well in hot weather.

"Check up on vulnerable friends, family and neighbours to make sure they stay hydrated, keep cool and know how to keep their homes cool."

The UKHSA recommends closing curtains indoors, checking for faults in fans and fridges, and avoiding physical exertion during the hottest part of the day.

Check this page throughout the day for live updates from Hertfordshire.

Met Office forecasts cooler weather to end week

Weather forecasters at the Met Office have released their Monday afternoon forecast, which suggests the UK's warmest night on record could begin this evening.

Hertfordshire will remain under a red weather warning for "extreme heat" on Tuesday, July 18, with the warmest temperatures expected inland in the East of England.

The South West is likely to experience cooler temperatures and some showers tomorrow, with a westerly wind arriving from the Atlantic, pushing the warmer weather eastwards throughout the day.

The Met Office forecast includes "more manageable" heat for the remainder of the week.

Fans heading to Standon Calling, near Bishop's Stortford can expect dry, fine weather on Thursday, when Madness is set to headline the Hertfordshire festival.

%image(14510516, type="article-full", alt="Mud sliding at Standon Calling 2021 during a storm. This year's weather is set to be dry and fine, according to the Met Office's forecast in the early week")

%image(14510518, type="article-full", alt="A bather dives in at Jesus Green Lido in Cambridge, near the Hertfordshire border, today (July 18)")

Today's weather has brought temperatures in the mid-30s to the East of England.

Elsewhere in the country, a 16-year-old boy has died after getting into difficulty at a lake just 12 miles away from the Hertfordshire border.

According to Thames Valley Police, crews were called to an incident at Bray Lake near Maidenhead, Berkshire at around 11.45pm.

The boy was located at 1.30pm and was pronounced dead at the scene.

The Met Office says Wales has provisionally recorded its hottest day on record. The mercury hit 35.3C in Gogerddan, near Aberystwyth.

London Luton Airport runway melts amid 36C heat

Passengers on WizzAir, Ryanair and easyJet flights this evening are facing disruption due to a "runway defect" at London Luton Airport.

A portion of the runway melted, which grounded all flights departing and arriving at the Bedfordshire airport, which sits on the north Herts border.

Luton Airport departures resumed at 5.40pm.

%image(14510520, type="article-full", alt="Extreme heat has created a "runway defect" at London Luton Airport, grounding all flights (File picture)")

Police advice issued after dog found in 'hot car'

Police were called to a Premier Inn in South Mimms after a dog was found in a "hot car".

Officers launched a rescue effort and the Rottweiler was left needing emergency treatment, a Hertfordshire Constabulary spokesperson said.

They added that dogs left alone inside a car on a hot day can quickly become dehydrated, develop heatstroke or die.

Fires, barbecues and bonfires warning

Following a fire in Redbourn, near St Albans, on Sunday, July 17, firefighters urging residents not to hold bonfires in extreme heat.

A Hertfordshire Fire and Rescue Service spokesperson said: "We've already attended a large bonfire in close proximity to a field of dry standing crop in Redbourn.

"It is NOT necessary to have a bonfire in this heat. It is extremely likely to spread fast on such dry ground and you will end up with an unexpected visit from us.

"Help us to help you – we are likely to be very busy in the next few days.

"The Redbourn bonfire tired up two of our appliances to extinguish the fire, with firefighters having to wear breathing apparatus and heavy, thick fire kit in this heat.

"These resources could have been used for emergencies elsewhere."

The fire service spokesperson is also urging residents to follow barbecue safety advice.

This includes keeping a bucket of water or sand, or a garden hose nearby for emergencies, and making sure the barbecue is well away from buildings, fences, trees, shrubs and garden waste.

%image(14510521, type="article-full", alt="Hertfordshire Fire and Rescue Service attended a bonfire in Redbourn, and said it is not necessary to hold bonfires in extreme heat")

Leisure and sports advice from North Herts council

The UKHSA is urging members of the public to avoid physical exertion in extreme heat.

"Try to keep out of the sun between 11am to 3pm, when the UV rays are strongest," a spokesperson said.

"Drink plenty of fluids and avoid excess alcohol.

"Avoid physical exertion in the hottest parts of the day."

In North Hertfordshire, the district council has warned that its outdoor pools in Hitchin and Letchworth are due to be extremely busy.

A North Herts District Council statement reads: "We expect Hitchin & Letchworth outdoor pools to be very busy today and tomorrow due to the hot weather.

"When they reach maximum capacity, customers will only be allowed in on a one in, one out basis.

"For your wellbeing, we would discourage queuing outside in the sun and heat."

%image(14510522, type="article-full", alt="A couple cool off in the heat today (Monday, July 18)")

Disruption begins at schools and libraries

Hertfordshire County Council said some schools are disrupted today (July 18), with closures in the Hemel Hempstead and Potters Bar areas.

A statement on the council's website urges parents to contact individual schools directly if they are concerned about closures.

Some libraries in the county are set to close early.

An HCC spokesperson said: "Most of our services are operating as normal, however we are having to close three libraries early this afternoon (Bovingdon, Leverstock Green and Kings Langley).

"There may be some further disruption over the next few days."

Water supply warning for Hertfordshire

Affinity Water teams - who manage the supply throughout the Stort, Lee, Colne and Misbourne river areas - are "working very hard" to keep up with extra demand, a company spokesperson said.

They said: "We want to make sure we have enough water to go around for drinking, washing and cooking during the upcoming hot weather.

"Please avoid all non-essential water use now, such as hosepipes and sprinklers."

The Affinity Water spokesperson added: "We're busy taking care of your water which means that right now we're working very hard to keep water flowing to everyone to meet the extra demand - we know that having access to water is essential in this very hot weather."

%image(14510525, type="article-full", alt="Affinity Water is urging customers to avoid non-essential water use (File picture)")