September weather forecastKapaa, HI
September
Weather in September
September brings subtle shifts to the weather in Kapaa, Hawaii. While retaining the warm temperatures from August, this month sees a decline in the daylight hours. The sea remains pleasantly warm, beckoning swimmers and surfers to its shore. Wind speeds remain steady despite the transition to the next season. The flavorful Hawaiian autumn gradually starts to make its presence known.Temperature
In Kapaa, the average temperatures in September are the highest, with a peak at 79.7°F (26.5°C) and a low of 75.9°F (24.4°C).Humidity
In Kapaa, the average relative humidity in September is 76%.Rainfall
In Kapaa, in September, it is raining for 18.7 days, with typically 1.54" (39mm) of accumulated precipitation. Throughout the year, there are 218.4 rainfall days, and 22.13" (562mm) of precipitation is accumulated.Ocean temperature
With an average ocean temperature of 80.2°F (26.8°C), September is the month with the warmest seawater.Note: Water temperatures ranging between 77°F (25°C) and 84.2°F (29°C) are regarded as very warm, making swimming, diving, and similar water activities pleasurable for extended periods.
Daylight
The average length of the day in September is 12h and 16min.On the first day of the month, sunrise is at 6:20 am and sunset at 6:53 pm. On the last day of September, sunrise is at 6:28 am and sunset at 6:25 pm HST.
Sunshine
The average sunshine in September in Kapaa is 8.7h.UV index
With an average maximum UV index of 7, September is the month with the highest UV index. A UV Index value of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV rays for the ordinary person.Note: The daily high UV index of 7 in September translates into this advice:
Refrain from overexposure. Fair-skinned individuals could burn in under 20 minutes. Avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is most intense, and remember that not all shade structures provide full protection. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Notice! The reflection of water and sand increases the UV radiation significantly.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Kapaa, HI
- Average high temperature in September: 79.7°F
The warmest month (with the highest average high temperature) is September (79.7°F).
The months with the lowest average high temperature are February and March (73.2°F).
- Average low temperature in September: 75.9°F
The month with the highest average low temperature is September (75.9°F).
The coldest month (with the lowest average low temperature) is February (68.5°F).
Average pressure in September
Kapaa, HI
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is April (30.07"Hg).
The months with the lowest atmospheric pressure are September and October (29.98"Hg).
Average wind speed in September
Kapaa, HI
- Average wind speed in September: 11.1mph
The windiest month (with the highest average wind speed) is July (12.3mph).
The calmest month (with the lowest average wind speed) is January (10mph).
Average humidity in September
Kapaa, HI
- Average humidity in September: 76%
The months with the highest relative humidity are June, July, August, October and December (77%).
The month with the lowest relative humidity is January (75%).
Average rainfall in September
Kapaa, HI
- Average rainfall in September: 1.54"
The wettest month (with the highest rainfall) is March (2.52").
The driest month (with the least rainfall) is April (1.3").
Average rainfall days in September
Kapaa, HI
- Average rainfall days in September: 18.7 days
The month with the highest number of rainy days is August (21.1 days).
The month with the least rainy days is January (12.5 days).
Average sea temperature in September
Kapaa, HI
- Average sea temperature in September: 80.2°F
The best month for swimming (with the highest average sea temperature) is September (80.2°F).
The coldest month (with the lowest average sea temperature) is March (74.8°F).
Average daylight in September /
Average sunshine in September
Kapaa, HI
- Average daylight in September: 12h and 18min
The month with the longest days is June (Average daylight: 13h and 30min).
The month with the shortest days is December (Average daylight: 10h and 48min).
- Average sunshine in September: 8h and 42min
The month with the most sunshine is June (Average sunshine: 9h and 42min).
The month with the least sunshine is November (Average sunshine: 6h and 12min).
Average sunshine days in September
Kapaa, HI
- Average sunshine days in September: 5.3 days
The month with the most sunshine days is January (12.8 days).
The month with the least sunshine days is August (2.9 days).
Average UV index in September
Kapaa, 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
Kapaa, HI
- Average cloud cover in September: 38
The month with the most cloud cover is March (Cloud cover 47).
The months with the least cloud cover are January and September (Cloud cover 38).
Average visibility in September
Kapaa, 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).
