Like this (youtube video)
How high are you tossing the water from? More height will allow more time for cooling. Also, how are you tossing the water? There’s probably a trick to get it to come out in small droplets rather than big globs, to increase the surface area.
Well, it will work at some temperature down to absolute zero. Don’t you mean maximum temperature? 
Point of clarification: Should not your question actually be, "What is the maximum outside temp needed to do the tossed boiling water turns to snow trick? " Once you’ve determined the maximum temperature any temperature below it should generate the intended result.
The warmest temperature at which the trick works is variable. Dont listen to those “maximum” folks. 
Overall humidity will also influence it, and so will your ability to aerosolize the liquid. For example, if you put warm water in a spray bottle, you will probably get the effect you want even at -20 celsius. Of course, boiling water will wreck such a bottle… don’t burn yourself.
Snow making machines use hot water mixed with compressed air.
I think you won’t be able to do quite the same thing at some temperature above absolute zero. At some point the air would have liquified, and at some higher temperature where there was still gaseous air the water would freeze in the pan before you could throw it. But it does seem unlikely that is what the OP is referring to.
I am interested in the answer, too. A newscaster in Champaign did this the other night, and it’s not really that cold out. It might have been 6° or 7°, but I don’t think that’s cold enough for this to happen. She did say it was warm water, if that makes a difference.
A bucket of warm piss would make some really pretty yellow snow drifting down to the ground.
Just saying. 
Or get some red or blue food coloring and add to the warm water. You’ll get red or blue snow.
I guess some a carafe of stale coffee would give brown snow?
on the radio a news story related snow from utility steam discharge and weather person local to it said it would at 13F.
Presumably you do not get pretty, hexagonal snowflake crystals doing things this way. What do you get?
Just little ice cubes, or perhaps cylinders.
I have seen a TV reporter do it with a glass of water from street level when it was about -10C, whatever that is in F.
14°F, which isn’t really that cold at all (at least to me, where it gets colder than that 5-10 days a year). I’m doubtful that it would actually work though unless you were very high up or the droplets are very small (as in the steam **johnpost **mentions). That said, I have tried unsuccessfully to find some chart or formula to calculate how fast a droplet of water will freeze at a given temperature (for example, 10 seconds for a X mm diameter droplet in air at 20F, which presumably would be 5 seconds at 8F (2x the difference from 32F), and so on).
Also of interest, water doesn’t necessarily freeze until it gets as cold as -48C/-55F. This is especially true for pure water, including boiled water, which will have less impurities in it than tap water.
For the real (fool)hardy in extremely cold temperatures, just unzip and pee off of the roof of a tall building. Get someone to video it.
Having said that, I’m sure some frat boys Dopers will make a go of this after an evening of beer drinking.
Is the initial temperature of the water a factor in the way it seems aerosolize in the video? Someone mentioned snow machines above, I thought they used hot water so they wouldn’t freeze up. But maybe there’s something about hot water that helps the effect. Somehow the water has to release that heat before freezing, so it might have something to do with the way the water disperses and forms something snow-like instead of sleet-like.