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

May weather forecast and climate
Hilo, HI

May, the last month of the spring, in Hilo, is also a moderately hot month, with average temperature varying between 66.9°F (19.4°C) and 80.6°F (27°C).

Temperature

In Hilo, Hawaii, the average high-temperature is practically the same as in April - a still warm 80.6°F (27°C). The average low-temperature, in May, is 66.9°F (19.4°C).

Humidity

The average relative humidity in Hilo is 78.9%.

Rainfall

In Hilo, during May, the rain falls for 23.5 days and regularly aggregates up to 6.3" (161mm) of precipitation. In Hilo, Hawaii, during the entire year, the rain falls for 272.1 days and collects up to 84.4" (2144mm) of precipitation.

Ocean temperature

In Hilo, Hawaii, the average seawater temperature is 76.8°F (24.9°C). A person's cold intolerance, with sunshine, wind, and air temperature, are essential factors for enjoying swimming in 76.8°F (24.9°C) water. (FYI: The Olympic swimming competition requires a water temperature between 77°F (25°C) and 82.4°F (28°C).)

Daylight

In Hilo, the average length of the day is 13.1h.

Sunshine

In Hilo, the average sunshine in May is 5h.

UV index

March through September, with an average maximum UV index of 12, are months with the highest UV index in Hilo. A UV Index value of 11, and more, symbolizes an excessive health risk from the exposure to the Sun's UV radiation for the ordinary person.
The average daily UV index of 12 transform into the following instructions:
Practice all-important precautions. Light skin people may get burned in less than 5 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. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Even on cloudy days, a sunscreen with a minimum 30 sun protection factor should be generously applied and frequently re-applied, including after every swim or outdoor exercise. Beware! The reflection of water and sand dramatically increases exposure to the UV rays.

What is the temperature in May in Hilo?

In May, in Hilo, the average high-temperature is 80.6°F (27°C), and the average low-temperature is 66.9°F (19.4°C).

What is the average humidity in May in Hilo?

The average relative humidity in May in Hilo is 78.9%.

How much does it rain in Hilo in May?

In Hilo, Hawaii, in May, it is raining for 23.5 days, with typically 6.3" (161mm) of accumulated precipitation.

How warm is the water in May in Hilo?

In May, the average ocean temperature in Hilo, Hawaii, 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.

How many hours of daylight does Hilo have in May?

In May, the average length of the day in Hilo, Hawaii, is 13.1h.

How many hours of sunshine does Hilo have in May?

The average sunshine in May in Hilo, Hawaii, is 5h.

When is the highest UV index in Hilo?

Months with the highest UV index are March through September, with an average maximum UV index of 12.

What is the UV index reading in May in Hilo?

In May, the average daily maximum UV index in Hilo, Hawaii, is 12. A UV Index of 11, and more, symbolizes an extreme health threat from unsafe exposure to the Sun's UV rays.
Average temperature in May - Hilo, HI
  • Average high temperature in May: 80.6°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 May: 66.9°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 May - Hilo, HI
  • Average humidity in May: 78.9%

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

Average rainfall in May - Hilo, HI
  • Average rainfall in May: 6.3"

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 May - Hilo, HI
  • Average rainfall days in May: 23.5 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 May - Hilo, HI
  • Average sea temperature in May: 76.9°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 May / Average sunshine in May - Hilo, HI
  • Average daylight in May: 13.1h

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 May: 5h

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 May - Hilo, HI
  • Average UV index in May: 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).