So for some reason a pirate fleet spawned in a tiny lake up in the northeastern steppe; the lake right next to Alexandrea-Eschate.
And yes, it proceeded to spawn sea storm events for two turns in a row while my budding Saka Rauka army besieged the city, killing 2/3 of my remaining force, and crippling that campaign (only had 2 camps conquered, was deep in the red still).
So, if possible, let's not have pirates spawning in the Ferghana valley and magically summoning hurricanes from a body of water about the size of the island of Rhodes.
EDIT: I suspect this is a vanilla problem, though?