What is a heatwave?
When does hot weather become a heatwave?
In the UK, heatwaves are declared when temperatures meet particular thresholds for three days in a row.
These thresholds vary by area because, in a heatwave, temperatures must be high relative to the expected conditions of that place at that time of year.
So, for example, the minimum for London is 28C but in Edinburgh the minimum is 25C.
These conditions were met in numerous parts of the UK over the weekend and the Met Office confirmed that a heatwave is underway.
