Doesn't storm normally occurs in the summer? Does it also happen in the winter?
There are different types of storms. You might be thinking of a rainstorm but the speaker is probably referring to a snow storm here. Also, although we can predict general weather patterns for each season, it is also subject to various conditions like ocean currents, wind speed and direction, temperature, and so on. Thus, storms can happen during any season (although of course, it'll be extremely rare for a snowstorm to occur during the summer, for example).
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