Waimalu
Hawaii, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Waimalu, HI

September, the first month of the autumn, in Waimalu, is also a moderately hot month, with average temperature ranging between max 82°F (27.8°C) and min 75°F (23.9°C).

Temperature

August and September, with an average high-temperature of 82°F (27.8°C), are the warmest months.

Heat index

In September, the average heat index is estimated at a tropical 87.4°F (30.8°C). Constant exposure and activity lead to possible fatigue. Prolonged exercise may result in heat cramps.
Note that heat index values are valued for light wind and location in the shade. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'apparent temperature', 'feels like', or 'real feel', is a measure of how hot it feels when the actual air humidity is factored in. Additional factors like activity, differences in body mass, height, and shape, clothing, and metabolic differences affect individual temperature impact. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.

Humidity

April through June and September, with an average relative humidity of 74%, are the least humid months in Waimalu.

Rainfall

In Waimalu, it is raining for 19.5 days, with typically 1.46" (37mm) of accumulated precipitation. Throughout the year, in Waimalu, there are 208.4 rainfall days, and 16.5" (419mm) of precipitation is accumulated.

Ocean temperature

August through October, with an average ocean temperature of 80.6°F (27°C), are months with the warmest seawater in Waimalu.
Note: Water temperature between 77°F (25°C) and 84.2°F (29°C) is regarded as very warm and enjoyable by all. With these temperatures, water activities are pleasurable, without feeling uncomfortable for prolonged periods.

Daylight

In Waimalu, the average length of the day is 12.3h.

Sunshine

The average sunshine in Waimalu is 8.4h.

UV index

With an average maximum UV index of 7, September is the month with the highest UV index in Waimalu. A UV Index of 6 to 7 symbolizes a high threat to health from the exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 7 transform into the following instructions:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.

What is the warmest month in Waimalu?

August and September, with an average high-temperature of 82°F (27.8°C), are warmest months in Waimalu, Hawaii.

What is the temperature in September in Waimalu?

In Waimalu, in September, the average high-temperature is 82°F (27.8°C), and the average low-temperature is 75°F (23.9°C). In September, the average heat index (a.k.a. 'felt air temperature', 'feels like'), that combines relative humidity and air temperature, is estimated at 87.4°F (30.8°C).

What is the least humid month in Waimalu?

April through June and September, with an average relative humidity of 74%, are the least humid months in Waimalu.

What is the average humidity in September in Waimalu?

The average relative humidity in September in Waimalu is 74%.

How many days does it rain in September in Waimalu?

In September, in Waimalu, the rain falls for 19.5 days. Throughout September, 1.46" (37mm) of precipitation is accumulated.

What months are the ocean warmest in Waimalu?

August through October, with an average ocean temperature of 80.6°F (27°C), are months with the warmest seawater in Waimalu, Hawaii.

What is the ocean temperature in September in Waimalu?

In Waimalu, Hawaii, in September, the average water temperature is 80.6°F (27°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 Waimalu?

In September, the average length of the day in Waimalu is 12.3h.

How long on average sun shines in September in Waimalu?

In Waimalu, the average sunshine in September is 8.4h.

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

With an average maximum UV index of 7, September is the month with the highest UV index in Waimalu, Hawaii.

What is the UV index intensity in September in Waimalu?

In Waimalu, the average daily maximum UV index in September is 7. A UV Index reading of 6 to 7 represents a high health threat from the exposure to the Sun's UV radiation.
Average temperature in September - Waimalu, HI
  • Average high temperature in September: 82°F

The warmest months (with the highest average high temperature) are August and September (82°F).
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 humidity in September - Waimalu, HI
  • Average humidity in September: 74%

Months with the highest relative humidity are February and December (76%).
Months with the lowest relative humidity are April, May, June and September (74%).

Average rainfall in September - Waimalu, 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 - Waimalu, 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 - Waimalu, HI
  • Average sea temperature in September: 81°F

The best months for swimming (with the highest average sea temperature) are August, September and October (81°F).
The coldest months (with the lowest average sea temperature) are January, February, March and April (75°F).

Average daylight in September / Average sunshine in September - Waimalu, HI
  • Average daylight in September: 12.3h

The month with the longest days is June (Average daylight: 13.4h).
The month with the shortest days is December (Average daylight: 10.8h).

  • Average sunshine in September: 8.4h

The month with the most sunshine is June (Average sunshine: 9.9h).
Months with the least sunshine are November and December (Average sunshine: 6.3).

Average UV index in September - Waimalu, HI
  • Average UV index in September: 7

The month with the highest UV index is September (UV index 7).
Months with the lowest UV index are January, February, March, April, May, June, July, August, October, November and December (UV index 6).