We were at Princeville the first two weeks of December. 12 of the 14 days were rainy. Some days it rained 24 hrs straight.
Generally the northern part of Kauai, ie Princeville, is rainier than the southern part of the island, ie Poipu.
But not always: If the Kona storms come from the south the Poipu area gets blasted like it did the two weeks we were there. Flooding was severe down around Poipu this last December.
Sure sorry to hear January has been so rainy as we are planning on the first two weeks in Hawaii next January.
Sterling