Weather in September
September signals a gradual transition towards autumn accompanied by falling daylight hours and increased sea temperatures. In this month, the highest sea temperature of 80.5°F (26.9°C) is noted, at the tail end of the summer. A decrease in daylight marks this transition, with an average of 12.3 hours noted. The weather progression towards cooler climes and shorter days will continue into the next month. However, September's weather stays steady, not displaying strikingly unique or erratic weather conditions.
Ocean temperature
With an average ocean temperature of 80.4°F (26.9°C), September is the month with the warmest seawater.
Note: Between the temperatures of 77°F (25°C) and 84.2°F (29°C), water is considered very warm, providing pleasure in water activities without discomfort over lengthy periods.
Daylight
The average length of the day in September is 12h and 16min.
On the first day of September, sunrise is at 6:21 am and sunset at 6:54 pm. On the last day of the month, sunrise is at 6:30 am and sunset at 6:26 pm HST.