I think the main problem you could have is finger freezing or at least losing speed and dexterity. If you can keep the instrument more or less warm until the moment of playing, it will probably stay at a temperature higher enough to avoid actual freezing inside, as the air you exhale will be at about 37ºC.

Tell us how you finally managed this situation.

<Added>

37ºCelsius = 98 degrees Fahrenheit

Lera,
Is this some school band director's bright idea?
I don't think that at my age I would agree to play anything at a location that is 0 degrees. Yuo can't keep yur flute from freezing up during a longer piece. You can't possibly play in tune and if your keywork does't get damaged from the cold, your pads could very well be deformed from your breath moisture.

If it were me and I were disinclined to call of sick for the event, I'd get some junker flute and a couple of pairs of long thermal underwear, a thick coat and gloves. The operative word is layer, layer layer.

Oh Lera!! You poor girl!! I do hope you didn't take your nice main flute out there. That is crazy! If you think that is bad then listen to this story... One of the reasons I despise many band directors!!!!! (Not all are bad, of course

I was awoken one night about two months ago when it was freezing temperatures outside to a local HS band practicing. Or should I call it blaring. lol!! The kicker was that it was 3:45 AM!!!! I like many others called the police to complain. The good old police couldn't do anything about the noise because they said it was a school function. Ahhh.... that is the good old South for ya! The school is located about a mile and a half from us. If that was my kid in that band I would have REFUSED to let them participate and raise quite a fuss with the band director too!

So Lera,

Now that the BD forced you through his athority and that grade issue to ruin your instrument, is he going to pay for the repair or buy you a new one that works? Which is it?

Yeah, really!!! I would hand that BD your repair bill!

i remember in high school we had a christmas parade we were required to play in. i also live in michigan and it begins to snow somewhere between august and september. i played on the schools brand new piccolo (about 2 weeks old) for a particular parade. it was snowing and freezing rain at the same time. it was so cold and there was just enough moisture in the instrument that the split e froze. and it stayed that way. the pads were so swollen that it needed all new pads. the repair was wonderful and couldnt be done by their contract service. they ended up taking it to an actual flute repair shop.

problem is they keep doing the parade, snow or shine.

oh, and i was sick for 3 weeks after, as was the rest of the band.

Sorry Lera, I am in a rare period of optimism and took those risks too lightly.
I understood you were to play at 0 degree and not much under that. Really sorry for what happened to your Simba and I hope you recover soon from your cold.

"i also live in michigan and it begins to snow somewhere between august and september"

EEGhads mbrowne, Where are you? Up there in the UP? Marquette? Basking in the tepid waters of Superior?

oh, lords no. i do have family that lives in the northern-most town in michigan, however.

i live in mid michigan. ish.