Gasoline can begin to deteriorate after only a short time in storage. When it's gone bad it has a very distinctive "skunky" odor and that means trouble for your motoring. Skunky gas can cause gum deposits in your fuel system that at best interfere with the performance of your engine. At worst, your engine won't run and you're probably looking at a costly repair bill.
Gasoline deterioration happens at a much faster rate when the temperature is high. So if you aren't going to use your vehicle much in the summer time, you should probably consider a gasoline stabilizer to slow the deterioration. In the winter deterioration happens at a slower rate because the gasoline is maintained at a lower temperature.
If you're only going to be parked for a few weeks to wait out a bit of foul weather, then it's unlikely any significant deterioration will occur. If, however, you're putting your vehicle away until spring time, the gasoline in your tank may give you a nasty surprise when you go to start it up after storage. This is a case where better safe than sorry applies and a stabilizer should be used.
To use a stabilizer, empty your fuel tank as much as possible. Stabilizers can preserve your gasoline for up to a couple of years but they can't fix what has already started to deteriorate. Once your tank is nearly empty, measure out enough stabilizer to treat a tank of gas; pour it in your tank; then fill your tank with gas to about 95% capacity. Filling your tank to 95% capacity minimizes the possibility of condensation and still leaves a bit of room for expansion and contraction.
A better alternative to using a stabilizer is to periodically operate your vehicle enough to require refilling your gas tank with fresh fuel. This not only resets the deterioration clock but serves two other purposes as well: 1) Bringing your vehicle up to operating temperature drives off moisture from the inside it's systems 2) It distributes lubricants so engine seals and other components continue to have a protective coating. Both are important factors to the health of your vehicle.
If you must store your vehicle for more than a few months, consider having it professionally done. Even with a stabilizer, long term storage can still result in fuel system problems. Removing all traces of fuel from the system and treatment of the resultant exposed surfaces may be required to assure minimal problems when you return to the road. The profession will also recommend such things as battery removal as well as other storage precautions.