Inclement weather patterns can greatly affect your survival plans. You won't be able to bug out during storms or travel far during heat waves. Similarly, if you know that it might rain in a few hours, you'll know when you need to seek out shelter before you're inevitably drenched.
For a good alert system, consider getting a survival weather radio. If the radio allows two-way communication, it may even be used to speak with survivors so you can ask them about the weather patterns in their area. A weather radio requires a lot of maintenance and upkeep, but it will be worth it.
Regular vehicles may not work as efficiently during and after SHTF scenarios. Dirt roads may become impassable, and regular streets may be flooded or filled with other vehicles. You and your group will require reliable means of transportation. This means you need to invest in a proper bug-out vehicle, such as an ATV or an SUV with proper off-road capabilities.
If you're not able to purchase a good vehicle, consider using a mountain bike, or better yet, begin training for long treks so you'll be able to travel far on foot. (Related: Low-tech transportation tools for the prepper: Do you have a wagon, wheelbarrow or yard cart?)
As a general rule of thumb, people can only survive up to three days without water. Several factors, such as age, overall health and level of activity, will change this. If you're in the process of bugging out of a disaster zone, this means those three days may be cut in shorter. This is why you need a reliable means of procuring water wherever you go.
Unfortunately, unless you come across intact and unopened bottles of water, the water you'll find might not be safe to drink. Most water out in the wilderness needs to be purified to eliminate any bacteria and parasites, and filtered to get rid of any dirt or sediment. Boiling water is your simplest way of purifying water, but some pathogens can still survive even after boiling. Consider other methods such as using straw-style filters or water purification tablets.
Aside from water, you also need a lot of healthy food to replenish all the energy you will spend from trying to survive. You can build up a strong and long-lasting storage of healthy food in your own home, provided that you have enough space and you don't plan to bug out anytime soon. However, if you do need to bug out, carrying around large packs of food is not ideal.
If you need to consider storage space, weight and the number of calories you can consume in one meal, consider meals, ready-to-eat (MREs). They are easy and reliable sources of energy, are lightweight and can withstand extreme temperatures, albeit with a possible tradeoff for shelf life.
The above-listed items will prove beneficial when you find yourself in a survival scenario, but don't forget that they're not all you need. You can use them to cover your bases and survive long enough to formulate a proper long-term survival plan.
Sources include: