September weather forecastWaipahu, HI
September
Weather in September
The month of September in Waipahu, Hawaii witnesses a slight decrease in temperature from the highs of summer, with the maximum temperature recorded as 82°F (27.8°C). Nonetheless, the tropical climate continues to prevail, making it an excellent time to visit the city. As we move into autumn, rainfall begins to pick up, with the month recording an average of 1.46" (37mm). However, September remains a sunny month, ample daylight contributing to outdoor explorations. An interesting weather detail observed this month is the sea temperature, hitting a high of 80.6°F (27°C), making beach visits and aquatic activities quite a lure.Temperature
During August and September, Waipahu registers its highest temperatures, averaging a high of 82°F (27.8°C).Heat index
September's average heat index is computed to be a tropical 87.8°F (31°C). If one continues to be active during enduring exposure, it could result in fatigue and heat cramps.Know that the heat index computations account for shaded terrains and slight winds. The heat index may scale up by 15 Fahrenheit (8 Celsius) degrees with direct sun exposure.
Note: The heat index, also known as 'real feel' or 'felt air temperature', provides an understanding of perceived warmth by combining temperature and relative humidity. Elements such as metabolic variations, pregnancy, and physical exertion can influence one's weather perception. Awareness of direct sun exposure is crucial as it has the potential to heighten the weather's effects, pushing up the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values remain especially vital for babies and toddlers. Typically, young kids are at a higher risk than adults since they sweat less. Also, the larger skin surface in proportion to their small bodies and the heightened heat production due to their active nature adds to their vulnerability.
Humidity
April through June and September, with an average relative humidity of 74%, are the least humid months.Rainfall
In September, the rain falls for 19.5 days. Throughout September, 1.46" (37mm) of precipitation is accumulated. Throughout the year, there are 208.4 rainfall days, and 16.5" (419mm) of precipitation is accumulated.Ocean temperature
With an average ocean temperature of 80.6°F (27°C), September is the month with the warmest seawater.Note: Water temperatures in the range of 77°F (25°C) to 84.2°F (29°C) are warm and delightful, ensuring comfort during water activities over extended periods.
Daylight
In September, the average length of the day is 12h and 15min.On the first day of the month, sunrise is at 6:15 am and sunset at 6:47 pm. On the last day of September, sunrise is at 6:23 am and sunset at 6:20 pm HST.
Sunshine
In September, the average sunshine is 8.4h.UV index
September is the month with the highest UV index, with an average maximum UV index of 7. A UV Index estimate of 6 to 7 represents a high health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: In September, the maximum UV index of 7 suggests this advice:
Sidestep overexposure. Individuals with fair complexions risk burning in fewer than 20 minutes. Avoid direct sunlight between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. Keep in mind that shade structures may not provide complete protection. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Watch out! Sand and water enhance the UV exposure you receive.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Waipahu, HI
- Average high temperature in September: 82°F
The warmest months (with the highest average high temperature) are August and September (82°F).
The months with the lowest average high temperature are February and March (75.4°F).
- Average low temperature in September: 75°F
The month with the highest average low temperature is September (75°F).
The coldest month (with the lowest average low temperature) is February (68°F).
Average pressure in September
Waipahu, HI
- Average pressure in September: 29.97"Hg
The month with the highest atmospheric pressure is April (30.06"Hg).
The months with the lowest atmospheric pressure are September and October (29.97"Hg).
Average wind speed in September
Waipahu, HI
- Average wind speed in September: 9.3mph
The windiest month (with the highest average wind speed) is July (11.3mph).
The calmest month (with the lowest average wind speed) is January (8.4mph).
Average humidity in September
Waipahu, HI
- Average humidity in September: 74%
The months with the highest relative humidity are February and December (76%).
The months with the lowest relative humidity are April, May, June and September (74%).
Average rainfall in September
Waipahu, HI
- Average rainfall in September: 1.46"
The wettest month (with the highest rainfall) is October (2.09").
The driest month (with the least rainfall) is July (0.71").
Average rainfall days in September
Waipahu, HI
- Average rainfall days in September: 19.5 days
The month with the highest number of rainy days is March (20 days).
The month with the least rainy days is January (13.5 days).
Average sea temperature in September
Waipahu, HI
- Average sea temperature in September: 80.6°F
The best month for swimming (with the highest average sea temperature) is September (80.6°F).
The coldest month (with the lowest average sea temperature) is March (75.7°F).
Average daylight in September /
Average sunshine in September
Waipahu, HI
- Average daylight in September: 12h and 18min
The month with the longest days is June (Average daylight: 13h and 24min).
The month with the shortest days is December (Average daylight: 10h and 54min).
- Average sunshine in September: 8h and 24min
The month with the most sunshine is June (Average sunshine: 9h and 54min).
The months with the least sunshine are November and December (Average sunshine: 6h and 18min).
Average sunshine days in September
Waipahu, HI
- Average sunshine days in September: 6.5 days
The month with the most sunshine days is January (12.3 days).
The month with the least sunshine days is November (6.2 days).
Average UV index in September
Waipahu, HI
- Average UV index in September: 7
The month with the highest UV index is September (UV index 7).
The months with the lowest UV index are January, February, March, April, May, June, July, August, October, November and December (UV index 6).
Average cloud cover in September
Waipahu, HI
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 44).
The month with the least cloud cover is January (Cloud cover 36).
Average visibility in September
Waipahu, HI
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
