Britain is heading into another heatwave this week with temperatures potentially reaching 36°C, adding further pressure to water supplies and an electricity system already tested by extreme heat this summer.
The Met Office expects temperatures to rise sharply from Tuesday, reaching 32°C to 34°C across parts of England and Wales on Wednesday.
East Anglia and south-east England could reach 36°C on Thursday as high pressure moves east of the UK and draws hotter air northwards.
The latest spell follows an extraordinary summer of heat and drought.
Half of England has already been declared in drought, after exceptionally low rainfall, with seven water company regions imposing hosepipe restrictions covering around 23 million people.
Environment Agency figures show 78% of England’s rivers are running below normal or lower, with around one in six classified as exceptionally low for the time of year. Reservoir storage has also fallen to 75.3%, around 7.4% below the seasonal average, while some rivers including the Thames at Reading have been tracking record-low flows.
Another prolonged hot spell will increase evaporation from soils, rivers and reservoirs while pushing up household and agricultural water demand.
Power pressure
It could also put fresh pressure on the electricity system.
NESO data from June showed higher temperatures increased transmission system demand, particularly overnight when solar generation was unavailable. During that heatwave, higher demand coincided with lower wind generation and reduced availability from some conventional power stations.
Gas supplied more than half of generation on three days, while NESO issued Electricity Margin Notices on 24 and 26 June because available supply margins had tightened. The operator said the heatwave was the major factor behind both notices.
Air conditioning remains relatively uncommon in British homes but NESO expects its use to grow significantly as summers become hotter, creating a new source of peak electricity demand.
Its future energy scenarios suggest around 14 million homes could have air conditioning by 2050, adding around 4.2TWh of annual consumption.
The latest heatwave therefore highlights two increasingly connected pressures.
Higher temperatures increase electricity use at the same time as drought reduces water availability for households, agriculture and some forms of energy generation.
The Met Office has warned temperatures will probably remain above average through much of August, with further hot spells possible and rainfall likely to remain below normal, particularly in southern Britain.
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