According to the Met Office's criteria, an official heat wave consists of three consecutive days where temperatures exceed a certain threshold. In Scotland and Northern Ireland, this threshold stands at 25 degrees Celsius (77 degrees Fahrenheit), while London and nearby counties require 28 degrees Celsius (82.4 degrees Fahrenheit). Most of England, eastern Scotland, and eastern Northern Ireland are expected to meet these heat wave criteria. Even areas that fall slightly short will experience above-average temperatures.

Furthermore, the UK Health Security Agency has issued yellow heat health alerts, which is their lowest warning level, for all counties in England until Tuesday. They highlight the potential health risks posed by elevated temperatures, especially for vulnerable populations such as the elderly.

As the heat wave approaches, residents are urged to stay informed and take necessary precautions to protect their health during this wave of heat.