Lightning, heavy rain and even hail have been forecast for the next few days and Rewind Festival at Scone Palace.
Met Office forecasters have issued a yellow “be aware” warning for on Saturday.
Meanwhile, England has been enjoying a heatwave and some areas have been warned to brace themselves for a dangerous temperatures.
Health officials issued an alert following forecasts that the mercury may reach 32C (90F) in London and East Anglia on Friday.
Rain is expected to follow the warm conditions, according to the Met Office.
A spokeswoman said: “Areas of heavy, thundery showers may develop over England and Wales from Friday night before moving north into Scotland on Saturday.
“The development of these is uncertain but, where they do form, some torrential downpours are possible with frequent lightning, large hailstones and strong gusts of wind.
“Significant flooding is possible and visibility is likely to be reduced. We don’t know exactly where these showers are going to fall but Fife, Perthshire, Angus, Kinross and Dundee are in the middle of the warning area.”
The bad weather is due to a body of warm air, known as the Spanish Plume, travelling up from north-west Europe.
The spokeswoman added: “On Saturday we’re looking at sunshine and showers, some heavy, and possibly thunder.”
Temperatures will start off cooler but increase over the weekend. Although on Friday the maximum will be around 17C, by Sunday there could be highs of around 21C.
The spokeswoman added: “It’s going to be cool along the coastline but inland it should be fairly warm. The weekend should be humid.”