September weather forecastNānākuli, HI
September
Weather in September
September in Nānākuli brings with it, changes reminiscent of a farewell to the summer. It presents an increased level of rainfall, observing a recorded rainfall of 1.26in. The tendencies of change are persistent, as the city transitions into cooler months. The change from August to September is subtle but palpable, providing a pleasant blend between varying elements.Temperature
Nānākuli experiences its warmest period in August and September, averaging a high-temperature of 81.7°F (27.6°C).Heat index
The heat index for September is computed to be a hot 86°F (30°C). If one continues to be active during exposure, it might cause tiredness and subsequent heat cramps.It is important to note that the heat index values are for shaded areas and light wind scenarios. Direct sunlight exposure may result in a rise of the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is a numerical representation of warmth when taking temperature and moisture levels into account. The impact of weather is individual, with diverse individuals experiencing it differently due to variations in body mass, height, and activity levels. Direct sun rays can make one feel hotter, potentially raising the heat index by 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Children usually face more risks than adults as their ability to sweat is less. Additionally, their larger skin surface in relation to their petite bodies and higher heat output due to their activities increases their vulnerability.
Humidity
January, April through June, August through November, with an average relative humidity of 74%, are the least humid months.Rainfall
In September, the rain falls for 18.9 days. Throughout September, 1.26" (32mm) of precipitation is accumulated. In Nānākuli, during the entire year, the rain falls for 196.3 days and collects up to 14.72" (374mm) of precipitation.Ocean temperature
September is the month with the warmest seawater, with an average ocean temperature of 80.6°F (27°C).Note: Temperatures between 77°F (25°C) and 84.2°F (29°C) in water are ideal for swimming, diving, and other activities, providing enjoyment and comfort for extended durations.
Daylight
The average length of the day in September is 12h and 15min.On the first day of the month, sunrise is at 6:16 am and sunset at 6:48 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 9.1h.UV index
The months with the highest UV index in Nānākuli are June through September, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high health vulnerability from unsafe exposure to UV radiation for average individuals.Note: A maximum high UV index of 7 in September translates into the following recommendations:
Take precautions against overexposure. Protection against sun damage is needed. To the best of your ability, limit your exposure to the sun between the hours of 10 a.m. and 4 p.m., when UV radiation is at its peak. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly. Alert! The Sun's UV rays are heightened by the reflection of sand and water.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Nānākuli, HI
- Average high temperature in September: 81.7°F
The warmest months (with the highest average high temperature) are August and September (81.7°F).
The month with the lowest average high temperature is February (75°F).
- Average low temperature in September: 75.9°F
The months with the highest average low temperature are August and September (75.9°F).
The coldest month (with the lowest average low temperature) is February (69.1°F).
Average pressure in September
Nānākuli, 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
Nānākuli, HI
- Average wind speed in September: 9.6mph
The windiest month (with the highest average wind speed) is July (11.6mph).
The calmest month (with the lowest average wind speed) is October (8.8mph).
Average humidity in September
Nānākuli, HI
- Average humidity in September: 74%
The month with the highest relative humidity is December (76%).
The months with the lowest relative humidity are January, April, May, June, August, September, October and November (74%).
Average rainfall in September
Nānākuli, HI
- Average rainfall in September: 1.26"
The wettest month (with the highest rainfall) is March (1.81").
The driest month (with the least rainfall) is July (0.67").
Average rainfall days in September
Nānākuli, HI
- Average rainfall days in September: 18.9 days
The month with the highest number of rainy days is September (18.9 days).
The month with the least rainy days is January (13.8 days).
Average sea temperature in September
Nānākuli, 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
Nānākuli, 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: 9h and 6min
The month with the most sunshine is June (Average sunshine: 10h and 48min).
The month with the least sunshine is November (Average sunshine: 6h and 36min).
Average sunshine days in September
Nānākuli, HI
- Average sunshine days in September: 6.6 days
The month with the most sunshine days is January (11.8 days).
The month with the least sunshine days is November (6.4 days).
Average UV index in September
Nānākuli, HI
- Average UV index in September: 7
The months with the highest UV index are June, July, August and September (UV index 7).
The months with the lowest UV index are January, February, March, April, May, October, November and December (UV index 6).
Average cloud cover in September
Nānākuli, HI
- Average cloud cover in September: 32
The month with the most cloud cover is March (Cloud cover 38).
The months with the least cloud cover are January and September (Cloud cover 32).
Average visibility in September
Nānākuli, 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).
