What is "wind chill" all about?

It's not just that your brain thinks it's colder than it really is; because of the wind your skin is losing heat faster, and frostbite will occur more quickly than if there is no wind. Trust me on this - i'm from Saskatchewan, and our sadistic announcers on the CBC begin their weather casts on windy days in January with cheery little bulletins like: "Exposed flesh will freeze in 30 seconds."

Here in Virginia, the yearly concern is the opposite effect: heat index. You have to sweat more in our humid environment to get an equivalent cooling effect.

Conversely, in the winter the humidity compounds the wind chill.

What I want to know is at what temperature and/or wind speed does the humidity affect neither wind chill nor heat index.

I too grew up with those cheery little CBC weather reports. "Temperature is -25, but with the wind chill -58..." I always sort of disbelieved them, because I'd walk to school against the wind (a 25 minute walk) with my face exposed, and it wouldn't freeze. I always figured that either I was weird (but all my friends did it too) or the weather people exaggerated.

Conversely, in the winter the humidity compounds the wind chill.

Not so. All else being equal, the wind chill on a dry day will be more severe (ie, colder) than the wind chill on a humid day.