Hawaii has a tropical climate, with warm temperatures and relatively high humidity year-round, making it a reliable destination for diving in any season. Average air temperatures are around 24°C (75°F), with only slight variations throughout the year. Summer, from May to early October, brings the warmest, sunniest days and generally calmer seas, although it’s also considered off-season due to the small risk of cyclones. Winter is slightly rainier, but it’s also when waters around the islands come alive with humpback whales, which makes diving in Hawaii rewarding throughout the entire year.
General recommendations about the best time to visit Hawaii
Daytime temperatures in Hawaii typically range from around 20°C (68°F) in winter to 28°C (82°F) in summer, and water temperatures in Hawaii typically range from 24°C to 27°C (76°-81°F). Hawaii’s climate is tropical, but conditions are influenced more by seasonal swells than by dramatic temperature shifts. From May to October, the weather is warmer, drier, and generally calmer, while from November to April it brings slightly cooler air, increased rainfall, and powerful north swells that can entirely reshape dive conditions. September and October are often considered among the best months to visit, with warm water, excellent visibility, and more stable conditions across many islands.
Peak tourist seasons
Hawaii gets noticeably busier and more expensive during peak months like July and August, as well as around major US holidays such as Spring Break, Independence Day, and Christmas. For a quieter experience with better conditions overall, I’ve found the sweet spots to be April to May and October to November.
What you need to know about pelagic encounters
Seasonality in Hawaii becomes much more defined when you start looking at pelagic marine life. Humpback whale season typically runs from November through April, with peak activity in February and March, and I’ve found Maui often gets early sightings as soon as December. While you won’t dive with them, hearing humpback whales during a dive is a completely different experience – especially around areas like Molokini, where the season usually stretches from mid-December to mid-May, with the most consistent activity between January and March.
Manta rays, on the other hand, are far more predictable. Around Kona and the Big Island, encounters happen year-round. Still, conditions tend to align best from December to April and again from June to August, particularly on the well-known night dives, where sightings are remarkably consistent.
Hawaii also offers the chance to dive with hammerhead sharks off Molokai, but it’s very much an experience reserved for confident, experienced divers. At the easternmost tip of the island lies a known nursery area, where you might encounter schools of younger sharks and, on the right day, the occasional full-grown adult cruising through the blue. It’s a highly weather-dependent trip, involving a rough boat ride even in decent conditions, and sightings are never guaranteed—but your chances are noticeably higher during the summer months from June to August.
Average diving conditions in Hawaii
Diving conditions in Hawaii are generally consistent year-round, but they shift subtly with the seasons in ways worth planning for. Hawaii’s water temperature typically ranges from around 24°C (76°F) in winter to 26°C (79°F) in summer. Visibility is often excellent, between 20 and 30 meters, and can stretch even further on calm summer days. It is worth noting that winter swells can reduce visibility and limit access to the site.
Diving in Hawaii in January
January falls just outside the core winter season, coming right after the Christmas holiday rush, with warm water and slightly cooler, occasionally breezy conditions above the surface. It’s already a great time for whale activity around Maui and Molokini, while manta encounters around Kona remain highly reliable.
Conditions Oahu:
- Average water temperature at the surface: 24°C (76°F)
- Air temperature: min 21°C – 25°C (69°F-77°F)
- Average days of rain: 3
- Visibility: *** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 18°C – max 27°C (65°F-81°F)
- Average days of rain: 6
- Visibility: **** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 20°C – max 24°C (68°F-75°F)
- Average days of rain: 10
- Visibility: **** (1-5 stars)
Peak season:
US Christmas holidays in the last weeks of December and the first weeks of January
Diving in Hawaii in February
February is winter in Hawaii, bringing slightly cooler temperatures and a higher chance of rain, though dive conditions often remain good. It’s one of the best months for whale activity, especially around Maui and Molokini, where the season peaks, while manta sightings around Kona continue to be reliable.
Conditions Oahu:
- Average water temperature at the surface: 24°C (76°F)
- Air temperature: min 21°C – 24°C (69°F-75°F)
- Average days of rain: 4
- Visibility: *** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 18°C – max 27°C (65°F-81°F)
- Average days of rain: 5
- Visibility: **** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 20°C – max 24°C (68°F-75°F)
- Average days of rain: 12
- Visibility **** (1-5 stars)
Diving in Hawaii in March
March is considered winter in Hawaii, which can bring slightly higher rainfall. It’s also the start of US Spring Break, making the end of the month more crowded. It’s still peak season for whale activity around Maui and Molokini, while manta sightings around Kona remain highly consistent.
Conditions Oahu:
- Average water temperature at the surface: 24°C (76°F)
- Air temperature: min 21°C – 24°C (69°F-75°F)
- Average days of rain: 5
- Visibility: **** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 19°C – max 27°C (66°F-81°F)
- Average days of rain: 6
- Visibility: **** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 20°C – max 24°C (68°F-75°F)
- Average days of rain: 13
- Visibility: **** (1-5 stars)
Peak season:
Spring Break (different period, state by state, from mid-March to mid-April)
Diving in Hawaii in April
April is the transition between winter and summer, making it one of the best-balanced months to visit, though early April can still see some Spring Break crowds. Conditions are generally calm, and manta sightings around Kona remain in high season with very reliable encounters.
Conditions Oahu:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 22°C – 25°C (71°F-77°F)
- Average days of rain: 4
- Visibility: **** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 19°C – max 27°C (67°F-82°F)
- Average days of rain: 4
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 21°C – max 24°C (69°F-75°F)
- Average days of rain: 19
- Visibility: ***** (1-5 stars)
Peak season:
Spring Break (different period, state by state, from mid-March to mid-April)
Diving in Hawaii in May
May marks the start of summer in Hawaii and is generally considered off-season, with hotter, more humid conditions and the possibility of cyclones. Aside from a brief increase in visitors around Memorial Day, it’s typically a quieter month to travel.
Conditions Oahu:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 23°C – 26°C (73°F-79°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 20°C – max 29°C (69°F-84°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 22°C – max 25°C (71°F-77°F)
- Average days of rain: 23
- Visibility: ***** (1-5 stars)
Peak season:
Memorial Day (last Monday of May)
Diving in Hawaii in June
June falls within Hawaii’s summer off-season, with warmer, more humid conditions and the possibility of cyclones, though the ocean is often calm and inviting. The chance of Hammerhead sightings is higher than usual around Molokai and Maui, while the manta encounters peak again, especially around Kona and the Big Island.
Conditions Oahu:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 23°C – 27°C (73°F-80°F)
- Average days of rain: 2
- Visibility: ***** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 22°C – max 30°C (71°F-86°F)
- Average days of rain: 2
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 22°C – max 25°C (71°F-77°F)
- Average days of rain: 25
- Visibility: ***** (1-5 stars)
Peak season:
June is, in generally a peak tourist season.
Diving in Hawaii in July
Even though July is summertime and cyclones can still occur, it is also peak tourist season, especially around Independence Day. The chance of hammerhead sightings is higher than usual around Molokai and Maui, while the manta encounters peak again, especially around Kona and the Big Island.
Conditions Oahu:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 24°C – 27°C (75°F-80°F)
- Average days of rain: 2
- Visibility: ***** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 22°C – max 30°C (72°F-87°F)
- Average days of rain: 2
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 23°C – max 26°C (73°F-79°F)
- Average days of rain: 24
- Visibility: ***** (1-5 stars)
Peak season:
Tourist peak season for Hawaii and Independence Day (4th of July).
Diving in Hawaii in August
August is summertime, with the hot, humid air and chance of cyclones, but it’s also peak tourist time in Hawaii. The chance of hammerhead sightings is higher than usual around Molokai and Maui, while the manta encounters peak again, especially around Kona and the Big Island.
Conditions Oahu:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 24°C – 28°C (75°F-82°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 23°C – max 30°C (73°F-87°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 23°C – max 26°C (73°F-79°F)
- Average days of rain: 25
- Visibility: ***** (1-5 stars)
Peak season:
Tourist peak season for Hawaii.
Diving in Hawaii in September
September falls within Hawaii’s summer off-season, with warm, humid conditions and a continued risk of cyclones. It’s also one of the best times to visit for fewer crowds and lower prices, aside from a brief uptick around Labour Day.
Conditions Oahu:
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 24°C – 28°C (75°F-82°F)
- Average days of rain: 2
- Visibility: ***** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 22°C – max 30°C (72°F-87°F)
- Average days of rain: 3
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 23°C – max 26°C (73°F-79°F)
- Average days of rain: 20
- Visibility: ***** (1-5 stars)
Peak season:
Labour Day (1st Monday of September)
Diving in Hawaii in October
October is one of the quietest months in Hawaii, marking the end of the summer season with calmer conditions and fewer visitors. It’s also one of the best times to visit overall, with a good balance of weather, visibility, and crowd levels.
Conditions Oahu:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 24°C – 27°C (75°F-80°F)
- Average days of rain: 3
- Visibility: **** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 27°C (81°F)
- Air temperature: min 22°C – max 30°C (71°F-86°F)
- Average days of rain: 4
- Visibility: ***** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 23°C – max 26°C (73°F-79°F)
- Average days of rain: 15
- Visibility: ***** (1-5 stars)
Diving in Hawaii in November
November is one of the quietest months in Hawaii, with fewer visitors and a more relaxed atmosphere across the islands. It also marks the beginning of whale season, with the first sightings occasionally appearing toward the end of the month.
Conditions Oahu:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 23°C – 26°C (73°F-79°F)
- Average days of rain: 3
- Visibility: *** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 21°C – max 29°C (69°F-84°F)
- Average days of rain: 5
- Visibility: **** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 26°C (78°F)
- Air temperature: min 22°C – max 25°C (71°F-77°F)
- Average days of rain: 12
- Visibility: **** (1-5 stars)
Diving in Hawaii in December
December marks the start of the busy holiday season in Hawaii, with visitor numbers increasing around Christmas. It’s also when whale sightings begin around Maui and Molokini, while manta season picks up again around Kona.
Conditions Oahu:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 22°C – 25°C (71°F-77°F)
- Average days of rain: 3
- Visibility: *** (1-5 stars)
Conditions Maui:
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 19°C – max 27°C (67°F-81°F)
- Average days of rain: 6
- Visibility: **** (1-5 stars)
Conditions Big Island (Hawai’i):
- Average water temperature at the surface: 25°C (77°F)
- Air temperature: min 21°C – max 24°C (69°F-75°F)
- Average days of rain: 12
- Visibility: **** (1-5 stars)
Peak season:
US Christmas holidays in the last weeks of December and the first weeks of January.
Do you need more information to plan your trip to Hawaii?
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