SXM is a tropical island, mountainous, in the Trade Winds, with nothing but a couple thousand miles of open Atlantic Ocean to the Northeast. The end result is that the Trade Winds blowing out of the Northeast across all that open ocean pick up a lot of moisture. When they get to St. Martin they hit the mountains like Pic Paradise and climb up the slope into cooler air and lose their moisture as rain.

That's a long-winded way of saying that it probably will rain somewhere on the island, at sometime during each day, for at least a few minutes. That is why the long range weather forecasts call for a medium probability of rain every day. The only days with no rain forecast are during unusual conditions with a high pressure area sitting overhead.

Unless there is a tropical depression passing by the island there are very few washout days like we in the eastern US get when a warm front creeps northward along the coast.

So don't overthink weather forecasts... The norm is a few small showers scattered around the island in different locations at different times for a short duration each.

No big deal...