The smell of rain

If you're here, you might be wondering what petrichor means, anyway - or what it has to do with Halloween. 

Petrichor is a scent: the smell of rain as it begins to hit the ground after a long, hot spell. It's so distinct that you can often smell rain coming before it reaches you. It's earthy, dark, and deep; the small of hot pavement, soil, and dust; the smell of thunderstorms approaching. 

I associate the scent of petrichor with a nostalgic feeling of anticipation: The excitement of enjoying long nights of summer vacation, heralding the coming of Autumn and Halloween. 

You can read about some of the science behind the scent here: 

https://en.wikipedia.org/wiki/Petrichor

https://earthsky.org/earth/what-is-smell-of-rain-petrichor