A “kink” in the jet stream (above) pushing a mass of hot air from the Spanish plateau towards Britain is the reason temperatures have been so high this week.
The jet stream – a narrow band of fast moving winds high up in the atmosphere – normally flows in a fairly straight line from west to east, but in recent days it has meandered farther south towards Spain.
The Met Office explains that this phenomenon is known as a ‘Spanish plume’ – although they readily admit this is simply a “catchy name for a rather complex set of conditions".
The plume results in "very warm and humid air moving up from the Spanish plateau to the UK. If this meets cooler air from the Atlantic, the warm air can be forced rapidly upwards to produce thunderstorms".
It is believed the kink may have been caused by a cold front pushing the jet stream further south in the US which has in turn caused a set of knock-on effects across the Atlantic.