Heavy thunderstorms could cause danger to life, sudden flooding and power cuts as forecasters upgraded a weather warning.
A thunderstorm warning has been issued from the Met Office for the north-east of the country.
Five main areas across Scotland lie in the eye of the storm – Grampian, Central, Tayside, Fife and Highland
Thunderstorms will become more widespread across north-east Scotland during the early hours of Saturday morning, with a warning in place from 2am until 2pm.
The intense storms appear set to bring the British heatwave to an end.
Heavy rain, thunder and lightning is likely across much of the country with torrential downpours forecasted with a possible 20mm of rainfall in one hour.
Large hail, frequent lightning and strong and gusty winds are also forecast across much of the country.
Thunder and lightning will become less frequent and the risk of disruption will decrease on Saturday afternoon.
The Met Office have warned some homes and businesses could be at risk to flooding, with heavy rain set to create havoc on the roads.
Some damage to buildings could also occur with a high chance of lightning in many parts.
Those planning to travel have been urged to plan ahead with delays possible.
Some short term loss of power and other services is also likely.
A series of flood alerts has been issued by the Scottish Environment Protection Agency (Sepa).
The alerts cover Aberdeenshire and Aberdeen city, Caithness and Sutherland and Findhorn, Nairn, Moray and Speyside.
Warm overnight temperatures tonight are forecast to make sleeping difficult.
It is estimated it will be no cooler than 18C in Edinburgh and 17C in Glasgow.
Thursday saw the highest temperature recorded in the UK since 2015, with Wisley in Surrey hitting 35.1C.
The hot weather and very high afternoon temperatures have led to an amber warning for thunderstorms valid from 2pm to 8pm in the East Midlands and east of England.
“Fast flowing or deep floodwater is likely, causing danger to life,” the Met Office said of the areas covered by the amber warning.
Sepa confirmed water was now in “significant scarcity” in several areas, including Scotland’s north-east.
The government agency said it would take a month of “exceptional” rainfall to return levels to near normal.
By the end of July, Scotland is expected to hae suffered its driest six-month period for 34 years.