September weather forecast
Hawaii, USA

September in Hawaii signifies a gentle transition from the intense summer to the softer hues of autumn. The month witnesses temperatures ranging from 73°F (22.8°C) to 87°F (30.6°C). While the warmth of summer lingers, there's a subtle decrease in the highs compared to August.

September’s rainfall sees a slight uptick, signaling the onset of Hawaii's wetter season. Mount Waialeale on Kauai starts to register more frequent showers, a pattern that will continue intensifying in the succeeding months. Windward areas, with their verdant landscapes, receive more frequent drizzles, providing a refreshing contrast to the sun-parched leeward coasts, which still manage to enjoy ample sunny spells.

Regions of elevation, such as Mauna Kea and Mauna Loa, continue to boast clear, mesmerizing skies for a majority of the month. Stargazers can often capture the beauty of celestial events, with the cooler nights enhancing the overall experience.

When juxtaposed with August, September brings a milder touch to the climate. The threat from the Pacific hurricane season still looms, albeit diminishing as the month progresses. As September draws to a close, the Hawaiian archipelago readies itself for October, a month that traditionally sees more pronounced changes in weather patterns, especially in terms of rainfall.

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• Honolulu - September »
  With an average ocean temperature of 80.4°F (26.9°C), September is the month with the warmest seawater in Honolulu, Hawaii. The months with the lowest humidity in Honolulu are April, May, September and November, with an average relative humidity of 74%.
• Hilo - September »
  In September, the average ocean temperature in Hilo is 79.3°F (26.3°C). In Hilo, in September, it is raining for 19.2 days, with typically 1.81" (46mm) of accumulated precipitation.
• Kailua - September »
  The temperatures in Kailua reach their highest averages in September, with highs of 80.6°F (27°C) and lows of 77°F (25°C). In Kailua, in September, the average water temperature is 80.4°F (26.9°C).
• Kaneohe - September »
  With an average ocean temperature of 80.4°F (26.9°C), September is the month with the warmest seawater in Kaneohe. The month with the warmest seawater in Kaneohe is September, with an average ocean temperature of 80.4°F (26.9°C).
• Kahului - September »
  September is the month with the warmest seawater in Kahului with an average ocean temperature of 80.1°F (26.7°C). The month with the warmest seawater in Kahului is September, with an average ocean temperature of 80.1°F (26.7°C).
• Ewa Gentry - September »
  June through September, with an average maximum UV index of 7, are months with the highest UV index in Ewa Gentry, Hawaii. In Ewa Gentry, in September, it is raining for 13.3 days, with typically 0.83" (21mm) of accumulated precipitation.
• Kihei - September »
  The month with the warmest seawater in Kihei is September, with an average ocean temperature of 80.1°F (26.7°C). September is the month with the warmest seawater in Kihei, with an average ocean temperature of 80.1°F (26.7°C).
• Wahiawa - September »
  The least humid month in Wahiawa is September, with an average relative humidity of 73%. The least humid month in Wahiawa is September, with an average relative humidity of 73%.
• Schofield Barracks - September »
  In Schofield Barracks, Hawaii, the months of August and September register the average highest temperatures, peaking at 87.1°F (30.6°C). Schofield Barracks's temperatures tend to hit their maximum during August and September, with an average high-temperature of 87.1°F (30.6°C).
• Wailuku - September »
  In Wailuku in September, during 8.1 rainfall days, 0.39" (10mm) of precipitation is typically accumulated. On the first day of September in Wailuku, Hawaii, sunrise is at 6:09 am and sunset at 6:42 pm.