The internet seems to think the answer is yes but we spent forever debating this and no one is 100% convinced yet so here we are, settling the bet, so to speak.

FAQ

1. What if it's bad or dangerous for other reasons besides dehydration?

Only dehydration matters for this market. Imagine the snow is clean, you have enough food, enough warmth, etc. Is it still a bad idea to eat snow? Specifically, does your hydration level go down by doing so?

2. What if the answer depends on the temperature?

If you have to go below the coldest temperature ever recorded on earth (-89.2 °C) before the answer is yes, then this resolves NO. If the answer is yes all the way up to 0 °C then this resolves YES. If the snow temperature below which eating snow dehydrates you is between those temperatures then this resolves proportionally. For example, if it's true for snow temperature below -44.6 °C then we'll call this half true and resolve to 50% YES.

3. Are you sweating at all?

No, it's just a friendly wager. Oh, you mean in the snow-eating scenario. Also no: if you were sweating then eating the snow would help you retain moisture simply by cooling you off and helping you sweat less. That would be cheating so we're stipulating that you're not sweating.

I won't resolve this without consensus among those of us debating out loud and will be transparent about our reasoning and recruit experts if there are reasonable objections in the comments. Note that I'm trading in this market myself.