The number of ultra-hot days we endure every summer is on the rise, figures show.

Met Office data cited in new Office for National Statistics (ONS) research shows there has been a 28% increase in the annual average number of “summer days” - where the maximum daily temperature is above 25C.

Summer days averaged 8.8 days in the most recent decade - 2013 to 2022 - compared with 6.9 days for the period between 1991 and 2020 and 4.5 days between 1961 and 1990.

Last summer’s heatwave - which saw a record UK temperature of 40.3C set in Coningsby, Lincolnshire - ensured 2022 was well above those averages, with 14.9 summer days recorded.

The ONS research also highlights the consequences of extreme temperatures in the summer. The figure below shows how deaths last summer spiked above the five-year average during “heat periods” where the mean temperature was above 20C.

There were 2,008 deaths in the UK on 19 July last year: the day the temperature record was set in Coningsby. This compares to the average number of deaths on this date between 2016 and 2021: 1,431.

Overall, the ONS found 3,271 excess deaths during the five “heat period” spells between June and August last year.

It said the cause of excess deaths showing the largest proportional increase during these 2022 heat periods - relative to the days preceding the heat-periods - was cardiac arrythmias (17.4%).

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“Overheating places additional pressure on the heart and lungs, and increases the risk from cardiovascular and respiratory diseases,” the ONS said.

It follows a warning from 2021 in the Climate Risk Independent Assessment that the number of heat-related deaths in the UK, fuelled by climate change, could reach 7,040 deaths per year by 2050.