Hi all,
I notice during the cold days, after I start my engine for 2-3 minutes, a weird high-frequency noise start appears and it will keep having it through out the drive.
For warm days, the noise doesn't appear.
<- Here is a youtube video trying to capture that sound (I stop the car at around 0:20 in the video and the noise was still there). It's louder in the front passenger seat.
The fit is around 40k miles. (2015 fit EX with CVT)

 

I can't hear it at all. Of course I'm an oldie and like they say, we oldies can't hear high frequency sounds.

 

Is the cabin fan on? It sounds like the cabin fan.

Possible isolation steps:
Turn the fan off, see if it's still there.
Listen with the fan on and off to both in cabin and under the hood.