IPA: /ˈstɔːrmiər/
KK: /ˈstɔrmɪər/
More turbulent or unsettled, often referring to weather conditions that are rough or violent.
The weather forecast predicts that tomorrow will be stormier than today.
Stormier → It is formed from "storm" (from Old English *storm*, meaning a violent disturbance of the atmosphere) and "-ier" (a comparative suffix indicating more). The word "stormier" means more stormy or having greater intensity of storms.
Think of a 'storm' being more intense or severe when you add '-ier' to it, which indicates a comparison.