Big Island or Kauai for best weather & golf in January?

I have not been to Kauai, but it seems that both are on the "sunny" sides of the island, so your chances of good weather in either are probably decent. That being said, of course it can rain on the sunny side. Of the cumulative 3-4 weeks that I've spent in Hawaii on the islands of Oahu, Maui and the Big Island, all based on the sunny side of the island, and all in the December/January timeframe, I've only experienced one day of rain...and it was quite the downpour...but I just spent the time at the aquarium, taking a nap (love rainy day naps), shopping, and walking the shore after the rain.

I was on the Big Island in January of 2005. We experienced absolutely no rain or any indication of such when on the Waikoloa side of the island. The only possible rain during our approximate five days there was on the other side of the island, but the weather was actually quite beautiful even on the wet side when we decided to explore Volcanoes National Park.

Since I don't golf, I can't offer anything there.

If I had to make this decision, it would probably be based on how much time to spend and what I hoped to be able to do (assuming there is more planned than golf). I love snorkeling, so my decision would partially be based on availability to good snorkeling. The Big Island really is big and it takes time to travel outside of the resorts of Waikoloa to anything else significant (I think it's about 40 mins to Kailua-Kona). I remember driving A LOT on the Big Island. Although I haven't yet been to Kauai, it is likely that with such a smaller island, the travel time to other interests would be shorter. Oahu was much more enjoyable to me as far as driving goes in comparison to both the Big Island and Maui.

Also, just looking at a satellite image of the areas, the scenery is going to be drastically different. Waikoloa is largely black volcanic rock landscape. While stunning and interesting, I personally enjoy the older weathered cliffs of Oahu more than the "new land" of the Big Island. Since Kauai is older than Oahu, I expect that Kauai would better fit my personal preference of scenery.

If your question is specifically about January weather, not island scenery, have you researched weather statistics just to see how rainfall compares on the two locations? It would probably be helpful.

My only experience in January was a two-week vacation. First week was Kauai, where it rained every single day. Poured rain every day. Tried to snorkel anyway, with full wetsuits, but nearly froze after just 20 minutes or so.

The second week we went to Hawaii, and had lovely, clear weather. We wondered if it's better to stay on the southernmost island in the winter months.

Statistically, Kauai is the rainiest of the Hawaiian islands. This is what makes it the most lush and green of all the islands. That being said, weather on any of the islands is so variable that on any given week the weather is only predictable about one week in advance. For example, I was in Poipu last January and it was sunny and beautiful almost every day but the locals said that before I arrived it rained heavily for 3 weeks straight. So the best you can do is pick the sunniest side of the island you want to visit, buy your tickets and pray.

I have been to the Big Island in January; we had wonderful weather in Kona and So. Kohala. My experience is that the chances of rain are greater on Kauai, even if you stay on the "sunnier" south shore. That said, I prefer Kauai to Big Island because of the shorter driving distances. The key to the Big Island, IMO, is not to try to see/do everything all over the whole island.