Lots of affirmations at eight

A double-negative, in English, 
Is a positive they say
A double-positive, in French,
Is what we call Yé-yé 

It's warming up down there at eight

 An arctic front due this weekend
Things will be getting colder
I thought I'd warm it up a bit
With Brazilian bossa-nova

Get this party going at eight

Yes, I've been a way a bit
How long has it been?
Either way, I'm back again
Plus, it's Halloween