Putting food in snow to keep it fresh during a winter emergency is one of the first things that comes to people’s minds. It makes sense because we’ve been conditioned to think that the mere presence of snow indicates that surrounding temperatures are below freezing. However, this isn’t the case thanks to properties of thermodynamics that are too intricate to fully-summarize here. The reality is that temperatures in and around snow can be much higher than we think, and this can cause food to spoil just as fast as it would if it were left out on the counter.
One of the problems with keeping preserving food outdoors is that temperatures will rise and fall throughout the day. Consequently, these ups and downs can provide the right breeding ground for bacteria and other microorganisms to form. Even if they go dormant after temperatures drop, they can come back to life after temperatures rise. Additionally, snow is full of air pockets, and these can allow for warmer air to move through and increase temperatures as well. This can happen even if the snow isn’t melting. Safely preserving perishable foods under refrigeration requires a stable temperature of between 33-40 degrees. Unfortunately, it’s impossible to regulate temperatures in snow found outside.
Energy from the Sun
Did you know that the energy found in the sun’s rays can melt ice and generate quite a bit of heat, even if the air temperature is well-below freezing? Much of the sensation of heat that we feel on summer days comes from warm air instead of through direct sunlight. Unfortunately, the energy from the sun can cause temperatures in and around snow to melt, and this can also raise the temperatures of foods stored in snowbanks or piles as well.
That being said, shady areas can be a little more temperature stable, and they may be suitable for temporary, emergency storage. However, it may still be better to err on the side of caution and use your best judgment instead of taking chances with your food supply.
One of the best, and most reliable, alternatives is to make ice and use it to keep your refrigerator or cooler at a safe temperature. Take any available container that you have, fill it with melted snow or water, and let it freeze outside. Put the containers and ice inside your fridge, and use that to keep temperatures cool. Put your food as close to the containers as possible, and you can expect to get up to four hours of cooling before needing to add more ice.
If you are using your freezer, you can expect temperatures to remain stable for up to 18 hours due to the way most freezers are insulated. In both cases, it’s important to pack them as full as possible in order to get and keep temperatures stable for as long as possible.
Finally, remember that opening and closing refrigerator or freezer doors or the lid on your cooler will dramatically-reduce the amount of time that temperatures will remain cold. Try to plan ahead so that you can retrieve items at once and minimize unnecessary trips.
So, the next time you experience a power outage in the winter, don’t panic. Your food will be good for hours before you need to start thinking of ways to keep perishables cool. Use that time to start gathering containers and making ice, and you can keep repeating the process as necessary until the power comes back on.