May is the second month of the dry season in Hawaii.
The weather in Hawaii in May becomes less humid and rainy, with the average amount of rainfall ranging from 9.8 mm (0.4 in) on Molokai Island to 243.4 mm (9.6 in) on Kauai Island.
The average maximum temperatures in May range from 23°C (73°F) to 27°C (81°F) across the islands, with the lowest average minimum temperatures being 14°C (56°F) on Maui and 15°C (59°F) on Kauai Island.
The seawater temperature remains relatively consistent, with an average temperature of 25.2°C (77.4°F) on Hawaii to 25.6°C (78°F) on Oahu Island.
Keep in mind that the weather can vary greatly depending on the island you are visiting. Continue reading to learn more about the weather on each Hawaiian island in May.
Average temperature
The table below displays the average high and low temperatures in May on the main Hawaiian islands.
In May, the average high temperature in the Hawaiian Islands ranges from 23°C (73°F) on Maui and Kauai to 27°C (81°F) on Oahu and Molokai.
The average low temperature ranges from 14°C (56°F) on Maui to 24°C (76°F) on Hawaii and Niihau.
| Island | Average High | Average Low |
| Hawaii | 25°C / 77°F | 24°C / 76°F |
| Maui | 23°C / 73°F | 14°C / 56°F |
| Oahu (Honolulu) | 27°C / 81°F | 19°C / 67°F |
| Kauai | 23°C / 73°F | 15°C / 59°F |
| Molokai | 27°C / 80°F | 19°C / 66°F |
| Lanai | 24°C / 76°F | 17°C / 63°F |
| Niihau | 26°C / 79°F | 24°C / 76°F |
| Kahoolawe | 25°C / 77°F | 20°C / 68°F |
As a point of reference, the whole year’s average maximum temperatures in the capital city of Hawaii, Honolulu, are shown in the graph below.
Average seawater temperature
The table below shows the average seawater temperature for each of the main Hawaiian islands in May.
In May, the average seawater temperature in Hawaii ranges from 25.2°C (77.4°F) on the island of Hawaii to 25.6°C (78°F) on Oahu and Niihau.
Overall, the seawater temperature in Hawaii is relatively consistent across the islands, with just a 0.4°C (0.7°F) difference between the highest and the lowest average temperatures.
| Island | Average Temperature |
| Hawaii | 25.2°C / 77.4°F |
| Maui | 25.4°C / 77.7°F |
| Oahu (Honolulu) | 25.6°C / 78°F |
| Kauai | 25.3°C / 77.5°F |
| Molokai | 25.4°C / 77.7°F |
| Lanai | 25.5°C / 77.9°F |
| Niihau | 25.6°C / 78°F |
| Kahoolawe | 25.5°C / 77.9°F |
For reference, the chart below presents the average seawater temperature across all months of the year for the Honolulu area.
Average rainfall
The table below gives an overview of the average rainfall and rainy days in May on each of the main Hawaiian islands.
May is a relatively dry month in Hawaii, with the average rainfall ranging from 9.8 mm (0.4 in) on Molokai Island to 243.4 mm (9.6 in) on Kauai Island.
The number of rainy days also varies, with 0 rainy days on Molokai and up to 23 rainy days on Kauai.
| Island | Total Rainfall | Number of Rainy Days |
| Hawaii | 58 mm / 2.3 in | 2 |
| Maui | 38 mm / 1.5 in | 4 |
| Oahu (Honolulu) | 20.7 mm / 0.8 in | 3 |
| Kauai | 243.4 mm / 9.6 in | 23 |
| Molokai | 9.8 mm / 0.4 in | 0 |
| Lanai | 32.2 mm / 1.3 in | 4 |
| Niihau | 83 mm / 3.3 in | 4 |
| Kahoolawe | 24 mm / 0.9 in | 2 |
The chart below provides more perspective, by showing the average rainfall by month in Honolulu, the capital city on Oahu island.
Hawaii weather in May – FAQ
Does it rain a lot in Hawaii in May?
The rainfall in Hawaii in May varies depending on the island.
In May, the total rainfall ranges from 9.8 mm (0.4 in) on Molokai to 243.4 mm (9.6 in) on Kauai. There are also varying numbers of rainy days, ranging from 0 days on Molokai to 23 days on Kauai.
Overall, May is considered a dry month in Hawaii, with the wet season starting in November.
Is Hawaii too hot in May?
The average high temperatures in Hawaii in May range from 23°C (73°F) to 27°C (81°F) across the islands, which is generally considered warm but not too hot.
The average low temperatures range from 14°C (56°F) to 19°C (67°F), which can be comfortable for some people but may be too cool for others.
Is it warm enough to swim in Hawaii in May?
The average seawater temperature in Hawaii in May ranges from 25.2°C (77.4°F) to 25.6°C (78°F) across the islands, which is generally considered warm enough to swim.
The air temperatures in May are also generally warm, with average highs ranging from 23°C (73°F) to 27°C (81°F) across the islands.
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