Well before a hurricane nears, I turn our freezer and the refrigerator freezer section to the lowest temperature. I fill clean empty plastic milk and juice bottles nearly, but not quite totally, full with water, cap tightly and place them in the freezer. This takes up the empty space with something that will hold the cold. While preparing for an actual hit, we try to eat up any ice cream (not difficult!). If a hurricane actually hits, I place a good piece of duct tape over the door to remind people not to open it expect in genuine emergencies. Food will keep safely for several days.
How to you know if the food is okay when you do open it? Toss any ice cream, naturally. Meat that is still very cold with some ice crystals can be safely cooked and eaten right away, but not re-frozen. Same for prepared foods - preferably heat in the oven or stovetop if you can, as microwave heating is uneven and may not kill germs. Plain raw vegetables and fruits, breads, juice concentrates, and so on are more forgiving. Even if mostly thawed out, if they are icy cold they can be refrozen, although quality and nutrients may suffer a little. Refreeze, but use as soon as possible. Another solution with fruit if you have a lot, is to add a little sugar, bring to a boil, cool, then refreeze.
Experience will tell you when your freezer is getting to the critical point. Naturally this depends some on the surrounding temperature; a power outage in a winter snowstorm may give you a lot more time if the freezer is in a cold room.
In extended power outages, after two days, many people in Florida start holding yard parties, cook up foods from the freezer and invite their neighbors. It's the right - and safe - thing to do.