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 height of temperatures in Halawa is seen during July through October, averaging a high-temperature of 82.4°F (28°C).

Rainfall

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

Ocean temperature

September is the month with the warmest seawater, with an average ocean temperature of 80.6°F (27°C).
Note: Engaging in water activities, such as swimming or diving, in temperatures from 77°F (25°C) to 84.2°F (29°C) is very pleasurable for extended periods, without any discomfort.

Daylight

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

Sunshine

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

UV index

In September, the average daily maximum UV index in Halawa is 11. A UV Index estimate of 11, and higher, represents an extreme threat to health from unsafe exposure to UV radiation for ordinary individuals.
Note: The daily maximum UV index of 11 in September interprets into the following advice:
Adopt every vital precaution, unprotected skin and eyes may burn rapidly. Limit direct sun exposure especially between 10 a.m. and 4 p.m., when UV radiation is at its peak. However, keep in mind that shade structures may not provide full sun protection. Using UVA and UVB-protective sunglasses and sun-protective clothing is effective against UV radiation. Despite the overcast weather, sunscreen with SPF of at least 30 should be applied liberally and reapplied often, particularly after swimming or an outdoor workout. Attention! The combination of sand and water reflections enhances UV ray intensity.