Heat Waves: Causes and Duration Explained | RainViewer Blog

TL;DR: A single very hot day is not a heat wave: the technical definition requires several consecutive days above what is normal for the season and the area. A heat wave lasts as long as a high-pressure system stays stationary, blocking cloud and rain Its duration depends on how long that system takes to move, not on the peak temperature A weakened jet stream, or one displaced north, can leave the system trapped for one or two weeks Large cities cross the heat-wave threshold before the countryside, through the urban heat island effect Knowing a heat wave is under way says nothing about when it