September weather forecastHaleiwa, HI
September
Weather in September
September, the first month of the autumn in Haleiwa, is also a moderately hot month, with temperature in the range of an average low of 75.7°F (24.3°C) and an average high of 81.7°F (27.6°C).Temperature
September is the month when Haleiwa experiences its warmest temperatures, averaging a high of 81.7°F (27.6°C) and a low of 75.7°F (24.3°C).Heat index
September's heat index is evaluated at a hot 86°F (30°C). With unrelenting exposure and activity, one might experience exhaustion, leading to potential heat cramps.One should be cognizant that the heat index values are tailored for shaded spots and mild winds. Direct sunlight can cause a surge in the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', quantifies the warmth felt when relative humidity is considered. A person's impression of weather can be shaped by several aspects, among them metabolic variations, pregnancy, and levels of physical activity. With direct sunlight, be aware that it might enhance the heat sensation, raising the heat index by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are quite important for babies and toddlers. Young kids are often more at risk than adults as they tend to perspire less. Besides, their skin surface is larger relative to their small bodies, and their increased heat output from their active lifestyle compounds their risk.
Humidity
May and September, with an average relative humidity of 74%, are the least humid months.Rainfall
In Haleiwa, in September, it is raining for 17.4 days, with typically 0.98" (25mm) of accumulated precipitation. In Haleiwa, during the entire year, the rain falls for 190.2 days and collects up to 11.65" (296mm) of precipitation.Ocean temperature
With an average ocean temperature of 80.2°F (26.8°C), September is the month with the warmest seawater in Haleiwa, Hawaii.Note: Water activities in temperatures ranging from 77°F (25°C) to 84.2°F (29°C) are pleasurable, without feeling uncomfortable even during extended periods.
Daylight
In September, the average length of the day in Haleiwa is 12h and 16min.On the first day of September, sunrise is at 6:15 am and sunset at 6:48 pm. On the last day of the month, sunrise is at 6:23 am and sunset at 6:20 pm HST.
Sunshine
In Haleiwa, the average sunshine in September is 8.6h.UV index
July and September, with an average maximum UV index of 7, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high threat to health from unsafe exposure to UV radiation for the average person.Note: An average UV index of 7 in September transforms into this advice:
Continue precautions and advocate sun safety advice. Deterrence of sunburn is indispensable. Stay in the shade and avoid direct Sun exposure from 10 a.m. to 4 p.m., a period when UV radiation is particularly strong, noting that parasols or canopies may not offer total sun protection. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Take note! The UV strength of the Sun elevates when reflected off water and sand.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Haleiwa, HI
- Average high temperature in September: 81.7°F
The warmest month (with the highest average high temperature) is September (81.7°F).
The month with the lowest average high temperature is February (75°F).
- Average low temperature in September: 75.7°F
The months with the highest average low temperature are August and September (75.7°F).
The coldest month (with the lowest average low temperature) is February (68.5°F).
Average pressure in September
Haleiwa, HI
- Average pressure in September: 29.98"Hg
The month with the highest atmospheric pressure is April (30.06"Hg).
The month with the lowest atmospheric pressure is October (29.97"Hg).
Average wind speed in September
Haleiwa, HI
- Average wind speed in September: 9.8mph
The windiest month (with the highest average wind speed) is July (11.6mph).
The calmest month (with the lowest average wind speed) is January (9mph).
Average humidity in September
Haleiwa, 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 May and September (74%).
Average rainfall in September
Haleiwa, HI
- Average rainfall in September: 0.98"
The wettest months (with the highest rainfall) are February and October (1.34").
The driest month (with the least rainfall) is July (0.63").
Average rainfall days in September
Haleiwa, HI
- Average rainfall days in September: 17.4 days
The month with the highest number of rainy days is March (17.7 days).
The month with the least rainy days is January (12.5 days).
Average sea temperature in September
Haleiwa, 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 (75.2°F).
Average daylight in September /
Average sunshine in September
Haleiwa, 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 48min).
- Average sunshine in September: 8h and 36min
The month with the most sunshine is June (Average sunshine: 9h and 54min).
The month with the least sunshine is November (Average sunshine: 6h and 12min).
Average sunshine days in September
Haleiwa, HI
- Average sunshine days in September: 6.5 days
The month with the most sunshine days is January (12.9 days).
The month with the least sunshine days is September (6.5 days).
Average UV index in September
Haleiwa, HI
- Average UV index in September: 7
The months with the highest UV index are July and September (UV index 7).
The months with the lowest UV index are January, February, March, April, May, June, August, October, November and December (UV index 6).
Average cloud cover in September
Haleiwa, HI
- Average cloud cover in September: 37
The month with the most cloud cover is March (Cloud cover 44).
The months with the least cloud cover are January and September (Cloud cover 37).
Average visibility in September
Haleiwa, 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).
