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

September weather forecast and climate
Hilo, HI

September, the first month of the autumn, in Hilo, is still a warm month, with average temperature ranging between min 69.6°F (20.9°C) and max 83.3°F (28.5°C).

Temperature

September is the warmest month, with an average high-temperature of 83.3°F (28.5°C) and an average low-temperature of 69.6°F (20.9°C).

Humidity

In Hilo, the average relative humidity is 79.2%.

Rainfall

In Hilo, during September, the rain falls for 24.3 days and regularly aggregates up to 4.6" (117mm) of precipitation. In Hilo, during the entire year, the rain falls for 272.1 days and collects up to 84.4" (2144mm) of precipitation.

Ocean temperature

The month with the warmest seawater in Hilo is September, with an average ocean temperature of 79.3°F (26.3°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.

Daylight

The average length of the day in September is 12.2h.

Sunshine

In Hilo, the average sunshine is 5.4h.

UV index

Months with the highest UV index are March through September, with an average maximum UV index of 12. A UV Index estimate of 11, and higher, represents an extreme health hazard from the exposure to the Sun's UV rays for average individuals.
The daily maximum UV index of 12 interpret into the following advice:
Take all required precautions, as unprotected skin and eyes can burn in minutes. 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. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. A broad-spectrum sunscreen of SPF 30+ should be liberally applied and re-applied every two hours, and immediately after an outdoor workout or a swim. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.

What is the warmest month in Hilo?

With an average high-temperature of 83.3°F (28.5°C) and an average low-temperature of 69.6°F (20.9°C), September is the warmest month in Hilo.

What is the temperature in September in Hilo?

In September, the average high-temperature is 83.3°F (28.5°C), and the average low-temperature is 69.6°F (20.9°C).

What is the average humidity in September in Hilo?

The average relative humidity in September is 79.2%.

How many days does it rain in September in Hilo?

In Hilo, Hawaii, in September, during 24.3 rainfall days, 4.6" (117mm) of precipitation is typically accumulated.

What is the month with the warmest ocean in Hilo?

With an average ocean temperature of 79.3°F (26.3°C), September is the month with the warmest seawater in Hilo. 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.

How warm is the water in September in Hilo?

In September, the average ocean temperature in Hilo, Hawaii, is 79.3°F (26.3°C). 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.

How many hours of daylight does Hilo have in September?

In Hilo, Hawaii, the average length of the day in September is 12.2h.

How many hours of sunshine does Hilo have in September?

In September, the average sunshine is 5.4h.

What are the months with the highest UV index in Hilo?

March through September, with an average maximum UV index of 12, are months with the highest UV index in Hilo, Hawaii.

What is the UV index reading in September in Hilo?

The average daily maximum UV index in September in Hilo is 12. A UV Index estimate of 11, and higher, represents an extreme health vulnerability from unprotected exposure to the UV radiation.
Average temperature in September - Hilo, HI
  • Average high temperature in September: 83.3°F

The warmest month (with the highest average high temperature) is September (83.3°F).
The month with the lowest average high temperature is February (78.8°F).

  • Average low temperature in September: 69.7°F

The month with the highest average low temperature is September (69.7°F).
The coldest month (with the lowest average low temperature) is February (63.5°F).

Average humidity in September - Hilo, HI
  • Average humidity in September: 79.2%

The month with the highest relative humidity is November (80.3%).
The month with the lowest relative humidity is February (76%).

Average rainfall in September - Hilo, HI
  • Average rainfall in September: 4.6"

The wettest month (with the highest rainfall) is March (10.6").
The driest month (with the lowest rainfall) is June (4.3").

Average rainfall days in September - Hilo, HI
  • Average rainfall days in September: 24.3 days

Months with the highest number of rainy days are July and August (26.8 days).
The month with the lowest number of rainy days is February (15.8 days).

Average sea temperature in September - Hilo, HI
  • Average sea temperature in September: 79.3°F

The best month for swimming (with the highest average sea temperature) is September (79.3°F).
The coldest month (with the lowest average sea temperature) is March (75.7°F).

Average daylight in September / Average sunshine in September - Hilo, HI
  • Average daylight in September: 12.2h

The month with the longest days is June (Average daylight: 13.3h).
The month with shortest days is December (Average daylight: 11h).

  • Average sunshine in September: 5.4h

The month with most sunshine is June (Average sunshine: 5.9h).
The month with least sunshine is November (Average sunshine: 3.8h).

Average UV index in September - Hilo, HI
  • Average UV index in September: 12

Months with the highest UV index are March, April, May, June, July, August and September (UV index 12).
The month with the lowest UV index is December (UV index 7).