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

September weather forecast and climate
Honolulu, HI

Waikiki beach viewed from above, with clear calm waters on the foot of Honolulu city, Hawaii, with the vast cityscape and mountains in the distance
Waikiki beach viewed from above, with clear calm waters on the foot of Honolulu city, Hawaii, with the vast cityscape and mountains in the distance
September is still hot with steady temperatures at 75.2°F (24°C) at its coldest and 89.6°F (32°C) at its warmest. The amount of rain increase during the month, raining for an average of eleven days to collect at 0.6" (15.2mm) and are usually light and don't interfere with the warm weather. The sun shines for up to ten hours in the daytime, heating the ocean to a steady average of 80.6°F (27°C). Locals indulge more in the ocean and outdoor activities because of the manageable weather outside. The humidity score in September is 65%.

What is the temperature in September in Honolulu?

The average high-temperature, in September, is 88.5°F (31.4°C), while the average low-temperature is 74.5°F (23.6°C). In September, the average heat index (a.k.a. 'felt air temperature', 'real feel'), that takes the relative humidity and factores it into the air temperature reading, is estimated at 99.1°F (37.3°C).

What is the average humidity in September in Honolulu?

The average relative humidity in September in Honolulu, Hawaii, is 65.5%.

How many days does it rain in September in Honolulu?

In Honolulu, during September, the rain falls for 6.9 days and regularly aggregates up to 6.5" (166mm) of precipitation.

What month is the ocean warmest in Honolulu?

September is the month with the warmest seawater in Honolulu, Hawaii, with an average ocean temperature of 80.4°F (26.9°C).

How warm is the water in September in Honolulu?

In Honolulu, the average seawater temperature in September is 80.4°F (26.9°C). For any water activity, surface water temperatures between 77°F (25°C) and 84.2°F (29°C) are considered as excellent and extremely pleasant for lengthened periods.

How many hours of daylight does Honolulu have in September?

The average length of the day in September in Honolulu, Hawaii, is 12.3h.

How long on average sun shines in September in Honolulu?

The average sunshine in September in Honolulu, Hawaii, is 9.3h.

What is the UV index reading in September in Honolulu?

The average daily maximum UV index in September in Honolulu, Hawaii, is 11. A UV Index estimate of 11, and higher, represents an ultimate hazard to health from unsafe exposure to the Sun's UV rays.
Average temperature in September - Honolulu, HI
  • Average high temperature in September: 88.6°F

The warmest month (with the highest average high temperature) is August (88.7°F).
The month with the lowest average high temperature is January (80.1°F).

  • Average low temperature in September: 74.4°F

The month with the highest average low temperature is August (75.1°F).
The coldest month (with the lowest average low temperature) is February (66.1°F).

Average humidity in September - Honolulu, HI
  • Average humidity in September: 65.5%

The month with the highest relative humidity is January (73.3%).
The month with the lowest relative humidity is August (64.1%).

Average rainfall in September - Honolulu, HI
  • Average rainfall in September: 6.5"

The wettest month (with the highest rainfall) is March (11.5").
The driest month (with the lowest rainfall) is June (6.2").

Average rainfall days in September - Honolulu, HI
  • Average rainfall days in September: 6.9 days

The month with the highest number of rainy days is December (9.7 days).
The month with the lowest number of rainy days is August (5.6 days).

Average sea temperature in September - Honolulu, HI
  • Average sea temperature in September: 80.4°F

The best month for swimming (with the highest average sea temperature) is September (80.4°F).
The coldest month (with the lowest average sea temperature) is March (75.7°F).

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

The month with the longest days is June (Average daylight: 13.4h).
The month with shortest days is December (Average daylight: 10.9h).

  • Average sunshine in September: 9.3h

The month with most sunshine is July (Average sunshine: 9.9h).
The month with least sunshine is December (Average sunshine: 6.4h).

Average UV index in September - Honolulu, HI
  • Average UV index in September: 11

Months with the highest UV index are June, July and August (UV index 12).
The month with the lowest UV index is December (UV index 6).