Good question, but let's clarify something, when we talk about facebook storms, we're not referring to actual weather storms, but rather to periods when the platform becomes extremely strict and starts banning accounts and rejecting ads without warning, especially if you work in gray areas like gambling or supplements.
The first major storm of this kind began around 2016, when facebook tightened its rules due to political pressure, since then, there have been several episodes, but there isn't a fixed number per year because each storm is different, what is clear, however, is that these waves usually last from a few weeks to a couple of months, and then things calm down until the next one hits, as for the months, the rule of thumb is that the strongest storms occur during election periods, especially in the United States in november every four years, presidential elections tend to trigger the biggest waves, but local elections in other countries can also ignite a firestorm, aside from that, the first few months of the year often bring algorithm changes that feel like minor storms.