September weather forecast
Kapaa, HI

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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

September, on average, is the warmest month in Kapaa, registering a high temperature of 79.7°F (26.5°C) and a low of 75.9°F (24.4°C).

Humidity

The average relative humidity in September in Kapaa is 76%.

Rainfall

In September, in Kapaa, the rain falls for 18.7 days. Throughout September, 1.54" (39mm) of precipitation is accumulated. Throughout the year, there are 218.4 rainfall days, and 22.13" (562mm) of precipitation is accumulated.

Ocean temperature

The month with the warmest seawater in Kapaa is September, with an average ocean temperature of 80.2°F (26.8°C).
Note: For any water activity, surface water temperatures from 77°F (25°C) to 84.2°F (29°C) are deemed perfect and extremely pleasing for enduring enjoyment.

Daylight

In Kapaa, 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 is 8.7h.

UV index

The month with the highest UV index in Kapaa is September, with an average maximum UV index of 7. A UV Index of 6 to 7 symbolizes a high threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum UV index of 7 during September translates into these guidelines:
Beware of overexposure. Fair-skinned individuals risk burning in less than 20 minutes. Minimize exposure to direct sunlight and seek shade from 10 a.m. to 4 p.m., when UV radiation is most intense, but remember that shade structures may not offer complete protection. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Take caution! The UV rays from the Sun gain strength from sand and water reflections.
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Frequently asked questions

What time of the year is the hottest in Kapaa?

The warmest time of the year in Kapaa, Hawaii, is September, with temperatures averaging a high of 79.7°F (26.5°C) and a low of 75.9°F (24.4°C).

What is the temperature in September in Kapaa?

During September, Kapaa experiences an average high-temperature of 79.7°F (26.5°C) and a low-temperature of 75.9°F (24.4°C).

What is the average humidity in September in Kapaa?

In September, the average relative humidity in Kapaa, Hawaii, is 76%.

How many days does it rain in September in Kapaa?

In Kapaa, during September, the rain falls for 18.7 days and regularly aggregates up to 1.54" (39mm) of precipitation.

When is the ocean warmest in Kapaa?

The month with the warmest seawater in Kapaa, Hawaii, is September, with an average ocean temperature of 80.2°F (26.8°C).

How warm is the water in September in Kapaa?

In Kapaa, the average seawater temperature in September is 80.2°F (26.8°C). For swimming, diving, and other water activities, temperatures between 77°F (25°C) and 84.2°F (29°C) are perceived as very enjoyable and pleasurable for prolonged periods without feeling uncomfortable.

What is the average length of the day in September in Kapaa?

In Kapaa, the average day length in September is 12h and 16min.

What time are sunrise and sunset in September in Kapaa?

In September, on the first day of the month, sunrise is at 6:20 am and sunset at 6:53 pm. On the last day of the month, in Kapaa, sunrise is at 6:28 am and sunset at 6:25 pm HST.

How many hours of sunshine does Kapaa have in September?

In September, the average sunshine duration in Kapaa, Hawaii, is 8.7h.

What is the month with the highest UV index in Kapaa?

The month with the highest UV index is September, with an average maximum UV index of 7.

What is the UV index reading in September in Kapaa?

In Kapaa, Hawaii, the average daily maximum UV index in September is 7. A UV Index of 6 to 7 symbolizes a high health threat from exposure to Sun's UV rays.

Average temperature in September
Kapaa, HI

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).

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Average pressure in September
Kapaa, HI

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).

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Average wind speed in September
Kapaa, HI

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).

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Average humidity in September
Kapaa, HI

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%).

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Average rainfall in September
Kapaa, HI

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").

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Average rainfall days in September
Kapaa, HI

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).

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Average sea temperature in September
Kapaa, HI

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).

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Average daylight in September /
Average sunshine in September
Kapaa, HI

Average daylight in September / Average sunshine in September - Kapaa, HI
  • Average daylight in September: 12h and 2min

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 4min

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).

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Average sunshine days in September
Kapaa, HI

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).

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Average UV index in September
Kapaa, HI

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).

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Average cloud cover in September
Kapaa, HI

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).

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Average visibility in September
Kapaa, HI

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).

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Kapaa, Hawaii, USA

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