Why we're unlikely to see the temperature hit 2022's record highs of 40C in the UK this year

Picture of Grafham Water from July 2022, during UK's historic heatwave.
Credit: PA
Grafham Water reservoir drying up in 2022's record temperatures. Credit: PA

Headlines have appeared speculating that temperatures could reach 40C (104F) in July in the UK this summer - but how realistic is the speculation? ITV News meteorologist Aisling Creevey looks at the evidence.

It was exactly a year ago that the first suggestion came - that the temperature could break 40C in the UK.

This time last year, the concept of recording 40C seemed almost unbelievable. Yet, remarkably on 30 June 2022, an American weather model known as the GFS, produced output that placed that high over multiple locations across the southeast of England.

Over the following days, forecasters were busy trying to understand if this could actually be possible, followed very quickly by the realisation that something extraordinary was going to happen in the UK

Two-and-a-half weeks later on 18 and 19 July 2022, the UK experienced an unprecedented weather event.

Over these two days historic temperature records were squashed and a maximum temperature of 40.3C was reached at Coningsby in Lincolnshire.

A total of 46 stations across the UK exceeded the previous UK record of 38.7C.

Across the country, new highs were recorded - a Welsh record of 37.1C in Hawarden, 34.8 in Charterfall in Scotland, while Castlederg in Northern Ireland hit 31.2C, just 0.1C from its high of the previous year.

And it seems that it is memories of last year's extraordinary temperatures - and recent Met Office warnings of a heatwave - that has prompted speculation of a repeat this year.

So could it happen again?

The short answer is - it's unlikely. If we were going to hit the same highs as last year, we would have started to see the early signs by now.

The Met Office describe a heatwave as "an extended period of hot weather relative to the expected condition of the area at that time of year", which means it is different in different parts of the country.

The map below shows those thresholds. 

Heatwave thresholds across the UK Credit: Met Office

The forecast for the first two weeks in July is for a very typically British July - brief warm spells of weather interspersed with spells of rain and showers.

The signal for the second half of July is perhaps looking warmer and this potentially where we could experience a heatwave (as per the definition given by the Met Office) but nothing extraordinary is currently being signalled in any of the output of any weather model at home or internationally.

What about the rest of Summer?  

As we approach August, heat waves are always possible.

However, this is where we start to lose noticeable amounts of daylight.

The length of a day can often be the extra ingredient responsible for breaking temperature records. During August, between two to four hours of daylight is lost, so all other things being equal, the likelihood of reaching 40C during this time also declines.

Is climate change affecting summers in the UK?

The short answer is yes.

Attribution studies are now undertaken after an exceptional weather event. The aim of the study is to understand by how much climate change may be responsible for an extreme weather event such as droughts, flooding and extreme heat.

The likelihood of reaching 40C in the UK is about 10 times more likely when compared with the pre-industrial climate.

If climate pledges are not met, this chance is likely to increase.

To find out the weather for the coming days, check out our forecast here.

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