September is one of the best months to visit Hawaii weather-wise.
September falls into the dry season in Hawaii. This is when the amount of rainfall and humidity is low, and there is a lot of sunshine.
In the capital of Hawaii, Honolulu, the average temperatures in September range from 24°C (75°F) to 31°C (88°F). The average rainfall is 17.8 mm (0.7 in).
The weather can vary from island to island. In some cases, the average temperature can be as low as 16°C (61°F) (Maui, Kauai) and the rainfall as high as 172.5 mm (6.8 in) (Kauai).
Keep reading to learn about Hawaii weather in September in more detail.
Average temperature
The table below shows the average high and low temperatures in September on each of the main Hawaiian islands.
The average high temperatures in Hawaii in September range from 25°C (77°F) to 31°C (88°F), while the average low temperatures range from 16°C (60°F) to 26°C (79°F).
The temperatures vary by island, with the highest temperatures typically found on Oahu (Honolulu) and a bit cooler on Maui and Kauai.
| Island | Average High | Average Low |
| Hawaii | 27°C / 81°F | 26°C / 79°F |
| Maui | 25°C / 77°F | 16°C / 60°F |
| Oahu (Honolulu) | 31°C / 88°F | 24°C / 75°F |
| Kauai | 25°C / 77°F | 16°C / 61°F |
| Molokai | 29°C / 84°F | 21°C / 69°F |
| Lanai | 27°C / 81°F | 19°C / 66°F |
| Niihau | 28°C / 83°F | 26°C / 79°F |
| Kahoolawe | 26°C / 79°F | 22°C / 72°F |
For context, the graph below shows the average maximum temperatures in the capital city of Hawaii, Honolulu, across the whole year.
Average seawater temperature
The table below shows the average sewater temperature in September on each of the main Hawaiian islands.
In September, the average seawater temperature in the Hawaiian islands ranges from 26.7°C (80°F) to 26.9°C (80.4°F). The temperatures are fairly consistent across the islands, with only slight variations.
The seawater temperature in Hawaii in September is warm and comfortable. This month is a great time for swimming, surfing, snorkeling, and other water activities.
| Island | Average Temperature |
| Hawaii | 26.7°C / 80°F |
| Maui | 26.8°C / 80.2°F |
| Oahu (Honolulu) | 26.9°C / 80.4°F |
| Kauai | 26.7°C / 80°F |
| Molokai | 26.9°C / 80.4°F |
| Lanai | 26.8°C / 80.2°F |
| Niihau | 27°C / 80.6°F |
| Kahoolawe | 26.9°C / 80.4°F |
For better perspective, the chart below shows the average seawater temperature in the Honolulu area cross the entire year.
As you can see, the temperature of seawater doesn’t get any higher in the other months than in September.
Average rainfall
The table below shows the average amount of rainfall and the number of rainy days in September on each of the main Hawaiian islands.
In September, the average rainfall in Hawaii ranges from 7.1 mm (0.3 in) (Molokai) to 172.5 mm (6.8 in) (Kauai). The number of rainy days in September ranges from almost 0 (Molokai) to even 21 (Kauai).
With the exception of Kauai, the amount of rainfall in Hawaii in September is generally low, with most islands receiving less than 50 mm (2 in) of rain.
| Island | Total Rainfall | Number of Rainy Days |
| Hawaii | 53 mm / 2.1 in | 2 |
| Maui | 34.7 mm / 1.4 in | 3 |
| Oahu (Honolulu) | 17.8 mm / 0.7 in | 3 |
| Kauai | 172.5 mm / 6.8 in | 21 |
| Molokai | 7.1 mm / 0.3 in | 0 |
| Lanai | 31.6 mm / 1.2 in | 4 |
| Niihau | 46 mm / 1.8 in | 2 |
| Kahoolawe | 24.2 mm / 1 in | 4 |
For more context, the chart below shows the average amount of rainfall by month in Honolulu, the capital city of Hawaii located on Oahu island.
Hawaii weather in September – FAQ
Is it rainy in Hawaii in September?
September falls into the dry season in Hawaii. It does rain in Hawaii in September but not as much as it does during other months that fall into the wet season, from November to April.
It also depends on where you are in Hawaii. Statistically, the lowest amount of rainfall in Hawaii in September is on Hawaii Island (16.2 mm / 0.6 in) and the highest on Kauai island (172.5 mm / 6.8 in), where it rains for 21 days during September.
Is September hurricane season in Hawaii?
Yes. The hurricane season in Hawaii is from June to November, with the peak in August and September.
The last time hurricane hit the Hawaiian Islands was Hurricane Iniki in September of 1992, which hit the island of Kauai.
Although it’s a very small risk that the hurricane would hit the Hawaiian Islands directly, there is still a chance of it happening.
The possibility of a hurricane approaching the islands usually creates uncertainty in travel plans and flights being canceled or postponed. Make sure you have good travel insurance when you travel to Hawaii in September.
What time does it get dark in Hawaii in September?
The sunset in the capital of Hawaii, Honolulu in September happens at 18:47 at the beginning of the month and at 18:19 at the end of September.
What should I pack for a trip to Hawaii in September?
For a trip to Hawaii in September, pack lightweight and comfortable clothing, as well as swimwear and beach gear for outdoor activities.
It is also a good idea to pack a light rain jacket or umbrella in case of rain, especially on the Hawaiian island of Kauai.
September is often warm and bright, so carry lots of sunscreen and a hat to protect yourself from the sun.
If you intend to go trekking or exploring, bring closed-toe shoes and a backpack to carry water and other items.
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