September weather forecast
Halawa, HI

As summer fades in September, Halawa's weather patterns begin to alter. The temperature, though persisting in its highs, notices a small dip at the lower end. A moderate increase in rainfall to 2" (51mm) signifies the onset of a moistening climate. The seas offer warmth, giving beachgoers respite in case of a downpour. The daylight duration commences a gradual descent, and the UV index begins to reduce as well.

Temperature

The months of July through October see the peak of Halawa's temperatures, averaging a high of 82.4°F (28°C).

Rainfall

In Halawa, in September, during 7 rainfall days, 1.97" (50mm) of precipitation is typically accumulated. In Halawa, during the entire year, the rain falls for 116 days and collects up to 54.96" (1396mm) of precipitation.

Ocean temperature

The month with the warmest seawater in Halawa is September, with an average ocean temperature of 80.6°F (27°C).
Note: Surface water temperatures ranging from 77°F (25°C) to 84.2°F (29°C) are seen as ideal and highly pleasant for extended enjoyment in all water activities.

Daylight

In September, the average length of the day is 12h and 15min.
On the first day of September, sunrise is at 6:10 am and sunset at 6:42 pm. On the last day of the month, sunrise is at 6:18 am and sunset at 6:15 pm HST.

Sunshine

The months with the most sunshine are May through September, with an average of 9h of sunshine.

UV index

The average daily maximum UV index in September is 11. A UV Index of 11, and more, symbolizes an ultimate health vulnerability from exposure to the Sun's UV radiation for the ordinary person.
Note: In September, an average UV index of 11 transforms into the following instructions:
Employ all critical precautions. Guarding against sun damage is essential. Stay in the shade and limit direct sun exposure between 10 a.m. and 4 p.m., when UV radiation is at its strongest. Remember, however, that not all shade structures provide full sun protection. Experience reduced UV exposure by about half when donning a wide-brim hat. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Be careful! The Sun's UV radiation is accentuated by reflecting off sand and water.