We are often asked when to snorkel Hawaii for the best conditions. The truth is you can snorkel in Hawaii year round. It is a tropical climate and the air temperatures are warm enough to get in the water any time of year.
That said, we believe that the best season to snorkel in Hawaii is summer. There are exceptions to this, but that is what we recommend. Read on for the reasons why we believe summer is best.
The most important thing when figuring out when to snorkel Hawaii is the condition of the water.
First, we like warm water. And Hawaii does not have the warmest of tropical waters, so going when it is not chilly is nice. The water temperature in Hawaii ranges from about 74°F in the winter to about 82°F at the end of the summer. So in the late summer that is not bad, and we can stay in the water for an hour or two, wearing a regular rash guard on top. In winter though, it is a bit chilly, particularly in the mornings, and so we like to wear a thin neoprene wet suit top. So we enjoy summer more.
Waves Size & Direction
Wave sizes, also known as swell, vary by time of year. The north swell that happens in the winter in Hawaii is well known as the best time to surf on the north shore of Oahu. The north swell also makes the Na Pali Coast on the north shore of Kauai inaccessible for the winter months. Obviously this means you won't be snorkeling those areas. There can be a south swell in the summer that is a result of the winter storms in the southern Pacific. But in our experience, the winter north swell is more consistent than the summer south swell, so once again, we prefer summer.
There are always exceptions to this as it is weather related and not completely predictable, so you may luck out and have no swell in the winter on the north shore. When this happens you are bound to see surfers moping around wishing the waves were back.
You can't decide when to snorkel Hawaii without taking into account the weather.
Rain, though not as cold in a tropical place like this, can put a damper on snorkeling. Clouds and rain block the sun making it harder to see underwater and the combination of rain and no sun can make you cooler in the water. And if you are from a place where it rains a lot and you are looking for a sunny tropical vacation, rain can suck. Hawaii receives most of it's rain between October and April. So, generally in choosing when to snorkel Hawaii with rain as the factor, we choose summer.
Something else to consider with rain is that the Hawaiian Islands have a rainy side and a dry side. On the Big Island and Maui, most all of the snorkeling is on the dry side, lowering the overall rain chances year round. There are exceptions to this too, like on the Big Island, Kona can have rainy afternoons in the summer. On Oahu and Kauai, the snorkeling spots are all around the island, so summer will decrease the chances of rainy days for your snorkeling there. And truthfully, rain is always a factor on Kauai.
Wind is almost always a consideration in Hawaii. The tropical trade winds from the northeast in Hawaii are pretty consistent year round. These trade winds create waves on the east facing shores, causing low visibility and wavy snorkeling conditions. The snorkeling on the Big Island and Maui are better generally than Kauai and Oahu because the snorkeling areas are not on the east side of the island. But, the winds affect the Big Island and Maui too because as the day heats up, the winds get stronger in almost all of the snorkeling areas. So, we recommend snorkeling in the mornings before the winds really pick up.
The air temperatures at sea level range from 79°F - 83°F in the winter and 85°F - 90°F in the summer. These temperatures are fine for snorkeling all year. The summer can feel hot and humid and if this is an issue for you plan your trip for another time.
In choosing when to snorkel Hawaii, you will also want to consider the cost of your trip and the sizes of the crowds you will encounter. High seasons for crowds and prices are mid-December through mid-April and mid-June through August. Expect everything to cost more; flights, car rentals and hotels. But if you only have certain dates you can go, take your chances.
The best time of year to snorkel in Hawaii is summertime, May through September. That is not to say that if you have vacation time at another time of year that you shouldn't go to Hawaii. On every island, in almost all weather conditions, you can normally find a snorkel spot that is protected and fun, all year round.
You may also find this site helpful in deciding when to snorkel Hawaii.