Weather forecasters today warned the North East to expect thunderstorms later this week as the heatwave breaks.
The Met Office warning applies for the whole East Coast from 2pm to 11.45pm on Friday, July 27.
The weather service introduced the new advisory for thunderstorms last month.
It says there is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail, or strong winds
Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
Spray and sudden flooding could lead to difficult driving conditions and some road closures.
There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.
The forecast is for scattered thunderstorms - and depending on where they fall, they could interfere with the opening of Sunderland International Airshow on Friday afternoon and evening.
A Met Office spokesman said: "Whilst many places are likely to remain dry, there is the potential for thunderstorms to develop during Friday afternoon, lasting well into the evening.
"Where these occur, expect torrential downpours with a much as 30mm of rainfall in one hour and 60mm in three hours.
"Large hail and strong, gusty winds will be additional hazards."