It's official - this week's hot weather in Hertfordshire has broken previous county records.

According to data from the Met Office and Norwich-based forecaster Weatherquest, the mercury hit 39.2C in Buntingford in East Herts yesterday (Tuesday, July 19).

The new Hertfordshire record is higher than the previous UK record - 38.7C - which was recorded at Cambridge University Botanic Garden on July 25, 2019.

Elsewhere in the region, John Davis, a weather enthusiast in Harpenden, recorded 38C at around midday.

The University of Hertfordshire observatory in Bayfordbury, between Hertford and Hatfield, recorded a maximum temperature of 38.9C at 3.20pm.

The mercury hit 39.6C at Woburn in Bedfordshire. The highest recorded temperature in the East of England now stands at 39.9C - recorded at the National Institute of Agricultural Botany, Cambridge and at Wittering, both in Cambridgeshire.

In London, 40.2C was jointly recorded St James's Park, next to Buckingham Palace, and Heathrow Airport - just 12 miles from Maple Cross in Hertfordshire.

The Comet: Sunbathers next to London Heathrow Airport, where the mercury hit 40.2C on Tuesday, July 19Sunbathers next to London Heathrow Airport, where the mercury hit 40.2C on Tuesday, July 19 (Image: Jonathan Brady/PA Wire/PA Images)

The Comet: Greenery and shade on St Peter's Street, St AlbansGreenery and shade on St Peter's Street, St Albans (Image: Will Durrant)

The Comet: An unseasonably empty Verulamium Park, St Albans, as temperatures soared into the high 30s across Hertfordshire on Tuesday, July 19An unseasonably empty Verulamium Park, St Albans, as temperatures soared into the high 30s across Hertfordshire on Tuesday, July 19 (Image: Will Durrant)

The Comet: An ice cream in St Albans on the hottest day ever recorded in HertfordshireAn ice cream in St Albans on the hottest day ever recorded in Hertfordshire (Image: Will Durrant)

The new UK record was set at RAF Coningsby, Lincolnshire, according to the Met Office, where a reading of 43.3C was recorded.

Dr Nikos Christidis, a climate scientist at the Met Office, said the UK could see highs of 40C or more every 15 years by the year 2100.

Dr Christidis said: "In a recent study we found that the likelihood of extremely hot days in the UK has been increasing and will continue to do so during the course of the century, with the most extreme temperatures expected to be observed in the southeast of England.

"Climate change has already influenced the likelihood of temperature extremes in the UK.

"The chances of seeing 40C days in the UK could be as much as 10 times more likely in the current climate than under a natural climate unaffected by human influence."

The Met Office has been responsible for keeping public weather records since April 1914.

The longest-running temperature record in the world is the Central England Temperature record, covering the Midlands and North West, which dates back to 1659.

According to climate scientists at the Met Office, 40C heat usually only occur once every 100-300 years.

Hundreds of Hertfordshire residents visited splash parks and outdoor pools throughout the county to make the most of the hot weather.

The Comet: A pedalo on Stanborough Lake, Welwyn Garden City, as temperatures soared into the high 30sA pedalo on Stanborough Lake, Welwyn Garden City, as temperatures soared into the high 30s (Image: Karyn Haddon)

The Comet: Julia, aged 11, and Natalie, aged nine, at the Welwyn Garden City splash parkJulia, aged 11, and Natalie, aged nine, at the Welwyn Garden City splash park (Image: Karyn Haddon)

The Comet: Anastasia, aged five, was one of hundreds of visitors to the splash park in Welwyn Garden CityAnastasia, aged five, was one of hundreds of visitors to the splash park in Welwyn Garden City (Image: Karyn Haddon)

The Comet: Dami Horstall, aged seven, goes dipping in the lake at Welwyn Garden CityDami Horstall, aged seven, goes dipping in the lake at Welwyn Garden City (Image: Karyn Haddon)

But the unusual temperatures brought disruption to commuters in the county, with all Thameslink and Great Northern trains cancelled north of London.

A line-side fire at Harrow forced rail firms to suspend trains between London Euston and Watford Junction in the late-afternoon.

Secretary of State for Transport Grant Shapps, who also serves as MP for Welwyn Hatfield, admitted it would take "decades" to upgrade travel infrastructure so that it withstands higher temperatures.

Mr Shapps told Sky News: "We're going to see this more regularly.

"We're going to see this more - because there's huge infrastructure to replace."

The Comet: A Greenline bus on St Peter's Street, St Albans, on the hottest day ever recorded in Hertfordshire (July 19, 2022)A Greenline bus on St Peter's Street, St Albans, on the hottest day ever recorded in Hertfordshire (July 19, 2022) (Image: Will Durrant)

The Comet: A travel disruption warning at London King's Cross in the morning of Wednesday, July 20, when trains through Hertfordshire were delayed due to railway damageA travel disruption warning at London King's Cross in the morning of Wednesday, July 20, when trains through Hertfordshire were delayed due to railway damage (Image: Yui Mok/PA Wire/PA Images)

The Comet: Passengers at London King's Cross wait for delayed trains on Wednesday, July 20, one day after a scorching heatwavePassengers at London King's Cross wait for delayed trains on Wednesday, July 20, one day after a scorching heatwave (Image: Yui Mok/PA)

Hertfordshire Fire and Rescue Service declared a "major incident" following several serious fires in the county.

In one of the largest incidents in the county, 12 firefighting units were summoned to a field fire at Codicote, near Welwyn.

Five units were sent to a large vehicle fire on the M1 between Watford and Luton, while six units extinguished a combine harvester fire at Buntingford.

The Comet: A field fire in Knebworth yesterday (Tuesday, July 19)A field fire in Knebworth yesterday (Tuesday, July 19) (Image: Dan Roberts)

The Comet: The aftermath of a field fire in the Knebworth area yesterday (July 19)The aftermath of a field fire in the Knebworth area yesterday (July 19) (Image: Dan Roberts)

According to the Met Office, temperatures in Buntingford and the rest of Hertfordshire are set to become much cooler.

Rain is expected to hit the county in the evening, while eastern portions of Hertfordshire are covered by a yellow weather warning for thunderstorms.

Overnight temperatures are expected to sit around 18C, with a cooler and cloudier 23C heat throughout Thursday and Friday.

Sunshine is expected once again on Sunday, July 24 and Monday, July 25.