Start with "It's so hot outside" then add something that's happened! 

Remember to keep it HP-appropriate. 

It's so hot outside all of the vehicles' tyres have stuck to the roads!

So hot outside the grass has stopped growing 

it's so hot outside the ice cream truck is selling soup

So hot outside it became a desert 

So hot outside I burnt in 3 mins 

its so hot outside my air conditioner couldn't keep up

So hot outside the water buckets dried up 

So hot outside the cold tap had warm water only 

So hot outside thermostat was off the scale 

So hot outside the rivers dried up