What is the reason for making a Sukka?

One of the miracles that occurred during the Exodus from Egypt was the presence of clouds surrounding the Jews from all sides, providing protection from the elements. The sukka reminds us of this miracle. We observe the mitzva of the sukka in autumn and not in the spring when the Exodus took place, though. This is because during the spring, people might think the sukka was just a pleasant relocation for the nice weather. In autumn it is cold and rainy; it is obvious that the sukka is built to remind us of the miracle, not for our pleasure.