This one's easy, anytime you can go. 😄Kauai really is an all year destination. Summer time is great for water sports
Because the ocean is calmer during the summer. Just keep in mind that school is out so there are more crowds everywhere.
It will be a little warmer but the breezes help and don't worry the Pono Kai has air conditioning.
The winter has more rain but if your escaping snow and cold like me a little rain is nice plus the whales are around and they are always fun to see. Crowds tend to be a little older as there are many snowbirds and schools are in session. Temps will be a little cooler but can still get in the 80's. The extra rain will help the waterfalls flow freely.
Spring and fall are considered shoulder seasons but are great times to visit. It may be a little less crowded because the snowbirds aren't there and schools are still in session so there aren't many families either. Flights and car rentals can be a little cheaper also.