I agree with what someone else said. The second paragraph of my answer would be "given the car has been parked outside overnight in a blizzard, it is likely that the damage has already been done, and the engine and its cooling system are frozen solid. This would make it impossible to start the engine or replace any of the coolant in the cooling system, but if by chance it were possible, I would propose the following:"

- methylated spirits. It contains 95% ethyl alcohol and 5% methyl alcohol. (Can vary but that's a safe mix to use). It is commonly found under the kitchen sink, in pantries or in cupboards where cleaning products are stored. It can be reasonably expected to be in the chalet because its often used to un-freeze frozen pipes.

Logic: Ethyl Alcohol is commonly used as antifreeze. These days it is secondary to the preferred Ethylene Glycol, but you can still obtain ethyl alcohol based antifreezes used for various tasks including cars.

It will assist by adding antifreeze properties to the coolant, and it will not cause corrosion.

Metho mixes perfectly with water, so you would want to run at least part water for safety. Id suggest perhaps 33% metho, the rest water to be safe. This will result in a non-combustible mix.

The test would be to mix up a solution of the same %'s I wrote above, and put it in a sealed container (not glass, just to be safe!) and to put it in the freezer over night. Another great idea would be to run the test near the car, to properly simulate what the car is experiencing as it will get the same temperature.

be sure to point out:

- It boils at 65-78 degrees. This is not ideal as cars can get hotter so the metho cant be used by itself. The 66% water will help raise this a little closer to 100.

- It is flammable, so mixing with water will improve its safety. It wont selfignite until 470 degrees when pure anyway so unless it leaks, there is little danger of self ignition within the cooling system.

- the bottle of metho will be flammable. Care needed. No open flames.

- wear gloves and eye protection. If stuck, ski goggles and ski gloves. They love that kind of stuff! Dont breath the fumes either.

- 33% was chosen as it is close to the percentages used in proper antifreeze. It also means you have the benefits of lowering the freeze temperature, but also the water will help raise the boiling temp to closer to 100% than metho is.

- You can also add a few tablespoons to your windscreen washer bottle to help de-ice the windscreen.

- Take care driving down the mountain. Watch for overheating and stop to cool if the temp starts to rise too much. At bottom of the mountain or nearest opportunity, fully slush the system and put in proper antifreeze. Dispose of the old antifreeze in an environmentally friendly manner

Assuming the water has not actually frozen and you are concerned that it might... and at best popped the frost plugs out of the block, split the hose or cracked the block... the obvious solution is to run the engine at idle and warm the coolant so it never gets to freezing point.

Acceleration of the heating can be completed by blocking off the grille with a piece of cardboard. If you do so, ensure that the heater is off until the engine begins to warm, the heater acts as another radiator (something that is useful to know if your engine begins to overheat in hot conditions). When the engine reaches normal operating temperature (making sure that the exhaust is not blocked by a snow drift) let it idle for a ten minutes and then turn it off (ensuring that the grille is blocked off - you don't want that snow settling in it or the wind cooling the radiator prematurely).

Ensure then that the engine is in gear after you turn it off (if a manual) or in park in an auto. Preferably, you don't want the handbrake on unless you are on a slope as you can actually freeze the mechanism on.

Repeating this process every hour or so will ensure that the engine coolant never actually cools - before starting the engine turn on the ignition but don't start and look at the coolant temp gauge - otherwise methylated spirits would be a good option.

Fully flushing the system at the first opportunity is recommended.

I have seen folk pour vodka into a radiator in desperation, but given that the cooling system holds maybe 11 litres and vodka is only about 40% w/v - a whole 750 ml bottle would only give a concentration of 2.7% which is probably not enough to make much difference.

To be honest, the temperature at most southern hemisphere ski fields doesn't really get cold enough to crack a block - but possibly balloon a hose though.

In Canada when I used to race on skis, we used to plug the rental car into a 110v outlet at the carpark as we had a block warmer - even with glycol, at forty degrees below (which is the same temperature for farenheit and centigrade - the only place on the whole scale that the temperature is the same) you have real worries about the cold... it was the only place where I didn't take my full face race helmet off at the end of a run from being too warm (even with all the vents on the helmet closed)...

The other part of the equation is at these polar ambient temperatures, battery performance is severely compromised. Apparently, the cold conditions make the reactions in a lead-acid battery very slow so some cars have a circuit to keep the battery warm and/or trickle charging at rest.

Which is a lot better than a trucker mate who worked in Whitehorse, Alaska - it was so cold there (fifty below or worse), that they used to light a fire under the block for an hour before they fired up the rig... then left it to idle for an hour to warm enough to run.