The number one thing you have to look after to stay prepared is yourself. In a disaster situation where there is no longer any electricy (and therefore no air conditioning) things can go south fast if you are not prepared for the heat. While this is a particular worry in desert and southern climes, it heat stroke can happen anywhere-- especially if your regular means of protection are not around.
If you've ever suffered from heat stroke, you know how awful it is. Not only will it make you pretty miserable in the moment, but the effects of heat stroke are lasting. Days, weeks, or even months may pass before you are back to being 100% and until that happens even a few minutes in the sun can send you reeling. Avoiding heat illness or injury should be very high on your list of priorities, especially with summer right around the corner.
The first step in preventing heat injuries is getting used to the heat. This means getting up off the couch and putting forth the effort necessary to work up a sweat. If what you are acclimated to is a long day in front of the television with the air conditioner on full blast, you will not make it long in the great outdoors when temperatures start soaring.
When it comes time to move your rear end or lose your life, you want and need to be confident that you will be able to deliver on the 'move it' as opposed to the 'lose it.' This means exercising and building up your endurance and tolerance to heat. Start small so you don't wind up in the hospital, but build yourself up to taking long hikes while carrying full gear and even running in the process. The best way to fight heat illness and injury is to get your body on good terms with heat in the first place.
Be sure to drink plenty of water to stay hydrated. Since our bodies cool themselves by sweating, that is valuable moisture lost that you will need to replenish. Remember the old adage of drinking eight glasses of water per day? That estimate does not take into consideration the possibility of running for your life or spending hours trekking through sweltering heat. You will thus have to increase your water substantially to compensate for moisture loss, but you will also have to consume water wisely as drinking too much too fast will cause cramps and can make you ill in other ways as well.
With this in mind, revisit your water plan for post-disaster situations. A gallon a day per person is a good idea.
A seemingly ironic way to help keep cool when it gets hot is by covering up, not only with sunblock but also with clothing. It may seem more logical to take clothing off as opposed to putting more on, but clothing can protect from harmful UV rays in addition to aiding your body in retaining essential fluids. This works when clothing absorbs sweat, slowing down the evaporation process and at the same time keeping your body cooler for a longer period of time.
Ever seen pictures of Bedouins in the deserts of North Africa? They are clothed head to toe!
To enhance this process even further, soak a bandana in water and tie it around your neck. Not only will it keep the sun off of your skin but it will aid in cooling your body down. You can even buy specialized neck wraps that serve this exact purpose. Don't forget to utilize sunglasses as well, especially if you are on or around water, as it is surprisingly easy to burn your retinas.
Also important is to rest as needed. Breaks are essential not only for your body but also your mind. Even a brief break every hour or so can help rejuvenate you and prepare you for what is to come as you continue on your journey. Whether in motion or at rest, practice breathing exercises. When you become winded, it may be tempted to breathe through your mouth, but this actually does more harm than good. In addition to drying out mucus membranes which in turn requires more fluid for rehydration, you process more useful oxygen by breathing through your nose.
As summer approaches, now is the time to start preparing for the hot temperatures and oppressive humidity that could be coming your way. As inconvenient as sweltering temperatures may be, they are a part of life for which we need to prepare.
It would be nice if the SHTF on a nice, breezy day but chances are Murphy's Law will dictate something else entirely. Because of that, you need to prepare to beat the heat so it doesn't beat you.