No one thinks they’re going to be trapped by whiteout conditions or separated from their group as night falls but it happens with alarming regularity. Don’t make things worse by being unprepared. These advanced Mylar emergency blankets cost less than 4 bucks each and weigh virtually nothing and yet can and do save lives. They’re waterproof, tear-resistant survival gear that comes in a pack of 5. As such there’s no excuse for not having them tucked away in your backpack or daypack when you set out. The very definition of essential survival gear for outdoorsmen of all stripes.
For global catastrophic risks the costs of food storage become impractical for most of the population  and for some such catastrophes conventional agriculture would not function due to the loss of a large fraction of sunlight (e.g. during nuclear winter or a supervolcano). In such situations, alternative food is necessary, which is converting natural gas and wood fiber to human edible food.
The Cold War era civil defense programs promoted public atomic bomb shelters, personal fallout shelters, and training for children, such as the Duck and Cover films. The Church of Jesus Christ of Latter-day Saints (LDS Church) long directed its members to store a year's worth of food for themselves and their families in preparation for such possibilities; but the current teaching advises only a three-month supply.
In 1980, John Pugsley published the book The Alpha Strategy. It was on The New York Times Best Seller list for nine weeks in 1981. After 28 years in circulation, The Alpha Strategy remains popular with survivalists, and is considered a standard reference on stocking food and household supplies as a hedge against inflation and future shortages.
The survivalist hard-on (yep, and I'll do it again, too) for prophylactics untouched by chemical pleasure-enhancers is the result of drilling deep (told you) into the magical properties of our latex friends. According to our research, these flexible, durable, waterproof wonders will be as much of a deciding factor in your dystopian longevity as fire and can openers.
Every year in the US about 150 people die while out and about in national parks, more than 1,000 die in hunting-related incidents and thousands of backcountry enthusiasts get in deep trouble and require a Search and Rescue team to save them; with dozens of those folks dying while awaiting rescue. Most fatalities are the result of poor preparation. Bad weather descends and people get lost. They wander without water or shelter, often injuring themselves in the process. If they survive they often suffer frostbite, hypothermia, dehydration, trench foot or some combination of them all.