How do you know if a jacket is showerproof?

[DorisShuttAgainstGhosts]

Just that really!

Seen quite a few nice jackets but can't tell if they're slightly waterproof (so able to deal with light shower as I dash from car to house to work style).

Anyone got a clue? I need a jacket for cooler weather, as I don't want to wear my heavy waterproof - but I live in Scotland so rain is an ever present threat!

I've never encountered a jacket that wasn't shower proof..

Oh. I didn't realise

It's just I know my fleece isn't showerproof - it just gets damp and then my clothes underneath do too. I sort of assumed that heavy cotton jackets wouldn't be either.