Here are the top 10 most popular Kauai Activities and Kauai Tours ranked from most popular to least based upon the the last decade of statistics from Tom Barefoot's Tours. You will also see what months of the year will provide you with the very best experiences and enjoyment of those activities determined by the last decade of accumulated data.

#1  Snorkeling

• Without question, the very best time of year to enjoy snorkeling on Kauai is going to be the summer months.  This is due to the weather and in particular to the surf conditions.  Kauai's surf conditions will vary greatly between summer and winter months.  On the north shores like the NaPali Coastline the ocean is generally flat in Summer time but huge and sometimes dangerous surf will often dominate the winter seasons.  The reverse is somewhat true with regard to the southern shorelines such as the Poipu area where you can have a somewhat modest 'south swell' during the summers and be mostly calm except for 'wrap around' current during the winters.  The NaPali Coast however is 'the spot' people want to visit so it can be a disappointment for many coming in the winter months expecting to enjoy this to not even have a single boat willing to take them there.  Though the actual summer months will be the very best for snorkeling on Kauai there are days between the summer and winter when there is a transition between the two and there can be absolutely spectacular snorkeling days in both the Autumn and the Spring.  

#2  Zipline Tours

• Obviously zipline tours will have nothing to do with surf conditions since they are all land activities.  The weather will be the primary consideration with regard to course conditions with a special consideration to wind which can and does effect some of the zip runs.  With these considerations in mind, the rainy and windy season in Kauai will generally be in the winter months and so the best conditions for enjoying a beautiful day on the course will be in the spring, summer and fall.  Keep in mind that winter can also have beautiful days as well but the likelihood of disappointment will be somewhat higher at those times.

• Once again, ocean conditions will have no effect upon a helicopter tour but certainly wind and rain can be factor.  Helicopter tours are quite often cancelled because of inclement weather with either too much rain, wind or cloud cover.  Because Kauai is often times the single wettest location on the planet, rain can obviously be a factor often but the most likely culprit in terms of seasons would be the winter time.  Of course winter is a very busy time of year because of people wanting to escape the snow and sleet in North America and Europe so it can be difficult getting reservations at these times as well.  The problem often arises when helicopter bookings have been made back to back for days straight and then bad weather will come in and wipe the slate clean.  Those booked clients will then attempt to get on flights later in the month and consequently twice as many people will be vying for the same seats and it can be somewhat taxing.  Sometimes people simply have to come in the winter.  Don't let this detour you.  Simply make your booking as far in advance as you can and hope for the best.  Your best option for optimum time of the year would obviously be summer time, late spring or early fall.  The summer season is also very busy so the single best thing you could do would be to make a summer booking and make it early.  (One caveat to this would be that Kauai occasionally has hurricanes. If these occur they will likely come in September or the months surrounding.  These are obviously unpredictable but keep this in mind).

• Kayak tours are divided into two types: ocean kayaking and river kayaking.  Obviously ocean kayaking would follow the same parameters as the 'snorkeling' category above and winter would not be the best time to visit the Napali coast or points north.  River kayaking would be mostly dependent on the weather with a heavy emphasis on rainfall.  The biggest rainy season on Kauai will be the winter and spring and 'flash floods' are not uncommon.  If there is a likelihood of an event like this your kayak company will hopefully terminate the event prior to your departure.  This may ruin your kayak experience but it certainly will provide for your safety.  The normally pristine and crystal waters of the rivers may become muddy during these times and that is no fun either.  The summer is the best time on these rivers as they are calm and gently flowing and provide a great experience.

• Dinner cruises on Kauai take place on both the north and the south shores of the island.  There is no question however that the most popular dinner cruise tours visit the NaPali Coastline.  This coastline is perhaps the most severely effected of any of the shorelines on the island by the severe winter wave activity.  These waves will surely wipe out any chance of cruising NaPali so you should not place your hopes very high on enjoying a dinner cruise to the NaPali Coast in the winter time.  Summer is your best bet, but you guessed it, most people have figured that out already and these dinner cruises can be hard, or impossible to get on.  Best bet here is to plan to go in the late spring or summer time and make your reservations as early as you can. 

• Finally we have come to a category that is almost bullet proof.  These tours obviously are on land and are not effected by ocean conditions but generally speaking, they are not effected by weather conditions either.  As you may know, half the fun of these ATV tours is getting dirty, muddy and wet so rain or wind usually will have no effect on the tour itself.  They generally will go out rain or shine.  This puts the ATV category of activities in the catbird seat in terms of being able to make bookings and enjoy your tour at almost any time of year.  

• If your luau is going to be cancelled, nine times out of ten it will be because of rain.  Since many of the events enjoyed at a luau are enjoyed outside, it is certainly a better idea to attend one when the weather conditions are perfect.  Yes, once again this will mean enjoying one in the spring, summer and autumn months.  They will no doubt be offered in the winter time as well but you do have a greater chance of having it rained out.  Often luaus will have portions of the luaus indoors so if it is not 'too crazy' with the weather they may still occur even with less optimum conditions.

• Airplane tours on Kauai are very popular and go to almost all the same places as the helicopters do but usually at a lesser cost.  Please refer to the helicopter section above as the details for this category are almost identical to that of the helicopter tours.

• This category is not quite as bullet proof as the ATV category above but these tours can often go out in semi-inclement weather.  It is ideal to go out in perfect conditions so this would likely refer to the summer months but they go through the rainy season just as well in the winter.  In fact one determination you should consider would be that you might want to consider booking a horseback riding experience that departs from the Poipu side of the island if you are wanting to go in the winter because that will be the drier coastline.  Also, you might get to ride on the beach as well.  

• Fishing charters on Kauai are effected by the weather, but the type of fish you catch will also greatly be determined by the seasons.  Of course the best conditions on the water will be in the summer months and the seas will likely be less choppy.  Most sea captains, regardless of the weather will attempt to steer to the calmer waters in any event.  Better ocean conditions will however be in the summers.  As far as the fish are concerned they have their own agenda.  
• Let's start with this: as an overall rule, summer months are generally the best months for fishing. If you have your heart set on a 500 pounder, this is the likely time of year you will snag the most coveted catch in Hawaii, the Pacific Blue Marlin. A greater likelihood will be the Ahi or Yellowfin Tuna and Hawaii waters are ripe with catches well over 75 lbs. The other popular fish you will find being freshly served at the local restaurants which also run strong during this season are the Mahi Mahi and the Ono. 
• Don't feel too slighted if you arrive in Kauai in the fall months as all varieties of Marlin are still plentiful in Hawaiian waters and to a lesser degree, Mahi Mahi and Ahi are still plentiful as well.
• As winter season approaches you will see a general trend toward less fish in numbers and also smaller poundage. This of course does not mean that your fishing trip is doomed as many fish are randomly pulled in at this time and don't forget that "the worst day of fishing is still better than the best day at the office".
• Springtime ushers in the runs of Mahi Mahi which progressively get larger and larger in size as the summer approaches and these can often be caught in great numbers on the same charter.