A heatwave in the UK is defined by the Met Office as at least three consecutive days with daily maximum temperatures exceeding a county-specific threshold, reflecting unusually hot weather for the time of year.
The heatwave threshold temperature varies across the UK. In Greater London it is 28 Celsius whereas in Northern Ireland it is 25 Celsius.
It is possible that a few places could meet the heatwave definition during Friday, Saturday and Sunday. At the moment, counties like Herefordshire and Worcestershire look most likely.
But a lot depends on whether showers develop over the bank holiday weekend.