They're different zones, they don't have connected weather. While the weather charts are roughly the same, there is a small chance that the weathers will not be aligned.

This image details all weather in all zones of the game (through ShB). The weather algorithm pulls an RNG that essentially creates a straight line through each weather grid. Look close, and you'll see that at the very bottom of Lavender Beds, the weather can be clouds, while the bottom of the Gridania zones remains rain. It will also be when you'll get Lightning in Central and East Shroud, or Clear skies in North Thanalan, etc.