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

December weather forecast and climate
Hilo, HI

The first month of the winter, December, is also a moderately hot month in Hilo, Hawaii, with temperature in the range of an average low of 65.1°F (18.4°C) and an average high of 79.3°F (26.3°C).

Temperature

In Hilo, the average high-temperature is almost the same as in November - a still warm 79.3°F (26.3°C). In Hilo, in December, the average low-temperature is 65.1°F (18.4°C).

Humidity

The average relative humidity in December is 78.7%.

Rainfall

In Hilo, during 20.6 rainfall days, 8.3" (211mm) of precipitation is typically accumulated. In Hilo, during the entire year, the rain falls for 272.1 days and collects up to 84.4" (2144mm) of precipitation.

Ocean temperature

In December, the average ocean temperature in Hilo is 76.8°F (24.9°C). Depending on a person's sensitivity to cold, with regards to sunshine, wind, and air temperature, a quick swim in 76.8°F (24.9°C) water may be enjoyable. (FYI: The official water temperature required for the Olympic swimming competition is 77°F (25°C) to 82.4°F (28°C).)

Daylight

With an average of 11h of daylight, December has the shortest days of the year in Hilo.

Sunshine

The average sunshine in December is 4.2h.

UV index

December is the month with the lowest UV index in Hilo, with an average maximum UV index of 7. A UV Index reading of 6 to 7 represents a high threat to health from the exposure to the Sun's UV rays for the ordinary person.
The daily maximum UV index of 7 interpret into the following advice:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. 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. Caution! The reflection of sand and water significantly increases the intensity of the Sun's UV radiation.

What is the temperature in December in Hilo?

In Hilo, in December, the average high-temperature is 79.3°F (26.3°C), and the average low-temperature is 65.1°F (18.4°C).

What is the average humidity in December in Hilo?

In December, the average relative humidity in Hilo is 78.7%.

How many days does it rain in December in Hilo?

In Hilo, during December, the rain falls for 20.6 days and regularly aggregates up to 8.3" (211mm) of precipitation.

How warm is the water in December in Hilo?

In December, the average ocean temperature is 76.8°F (24.9°C). Depending on a person's sensitivity to cold, with regards to sunshine, wind, and air temperature, a quick swim in 76.8°F (24.9°C) water may be enjoyable.

What is the month with the shortest days in Hilo?

With an average of 11h of daylight, December has the shortest days of the year in Hilo.

How many hours of daylight does Hilo have in December?

In December, the average length of the day in Hilo is 11h.

How long on average sun shines in December in Hilo?

The average sunshine in December is 4.2h.

When is the lowest UV index in Hilo?

With an average maximum UV index of 7, December is the month with the lowest UV index in Hilo, Hawaii.

What is the UV index reading in December in Hilo?

In Hilo, the average daily maximum UV index in December is 7. A UV Index reading of 6 to 7 represents a high health risk from the exposure to the Sun's UV rays.
Average temperature in December - Hilo, HI
  • Average high temperature in December: 79.4°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 December: 65.1°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 December - Hilo, HI
  • Average humidity in December: 78.7%

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

Average rainfall in December - Hilo, HI
  • Average rainfall in December: 8.3"

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 December - Hilo, HI
  • Average rainfall days in December: 20.6 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 December - Hilo, HI
  • Average sea temperature in December: 76.8°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 December / Average sunshine in December - Hilo, HI
  • Average daylight in December: 11h

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 December: 4.2h

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 December - Hilo, HI
  • Average UV index in December: 7

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).