Complex sentence: Ko Samet gets significantly less rainfall than Rayong Province, even though it is only a few kilometres offshore, and the island's "rainy season" extends only from May to July, and even during this season has less rain that other islands in Thailand.
Split into simpler sentences: Ko Samet gets significantly less rainfall than Rayong Province, even though it is only a few kilometres offshore. The island's "rainy season" extends only from May to July, but even during this season it has less rain that other islands in Thailand.