Climatology for Hilo International Airport (PHTO)
Topography and Geography
Hilo, Hawaii is located on the eastern shore of the Island of Hawaii. The Hilo International Airport is situated just east of the city center, south of Hilo Bay. Although the island is dominated by two volcanic mountains >13,000’ (Mauna Loa & Mauna Kea), PHTO is just above sea level (30’)
The topographical map below shows the Hawaiian Islands, which are dominated by high relief. A closer terrain view here shows the proximity of PHTO to the mountains of Hawaii.
Hilo, Hawaii is located on the eastern shore of the Island of Hawaii. The Hilo International Airport is situated just east of the city center, south of Hilo Bay. Although the island is dominated by two volcanic mountains >13,000’ (Mauna Loa & Mauna Kea), PHTO is just above sea level (30’)
The topographical map below shows the Hawaiian Islands, which are dominated by high relief. A closer terrain view here shows the proximity of PHTO to the mountains of Hawaii.
The topographical map above shows Hilo, HI situated on the east coast of Hawaii, on the windward side of Mauna Loa and Mauna Kea.
Courtesy of John Hopkins University
Courtesy of John Hopkins University
PHTO and the Hawaiian Islands are located below the 23rd parallel and are considered tropical.
Winds
Looking at the March wind rose for PHTO below, you can see the major difference between onshore and offshore winds.
Wind rose for PHTO for March. While offshore winds are more common in March, they are much lighter than the less frequent onshore winds.
Courtesy Natural Resources Conservation Service
Courtesy Natural Resources Conservation Service
In March, the most common wind is southwesterly (offshore), occurring nearly 16% of the time. These winds are generally light with winds < 6.5 kts (yellow) occurring ~11% of the time, and winds < 10.5 kts (red) occurring ~5% of the time. SW winds > 10.5 kts (blue, green, cyan) are not represented in the wind rose. Note that winds between South and West (S, SSW, SW, WSW, W) only show winds <10.5 kts (red & yellow). Onshore winds, however, (from SSE – NW) all have measurable percentages of wind speeds > 10.5 kts. Winds from these directions occur at similar frequencies, with all having percentages ~6%.
The highest 2 minute wind speed recorded at PHTO in March was 29 kts in 2002. The wind was NNE (onshore).
Temperature
With its proximity to the Pacific, PHTO has a relatively small daily temperature swing. Studying the daily almanacs for the scheduled forecast days (Mar 13, 14, 15, 16, 20, 21, 22, & 23), you can see an average of a 14F difference from the average high to the average low. During this period, the average high and low remained exactly the same (79F – 65F).
For each of those forecast days, the record highs chronologically are: 86F, 86F, 85F, 86F, 85F, 87F, 88F, 93F (7-15°F above average).
The record lows for the forecast days chronologically are: 56F, 56F, 57F, 56F, 57F, 60F, 59F, 59F (5-10°F below average).
On the other side of extremes, record high minimum temperatures chronologically are: 70F, 70F, 70F, 69F, 68F, 69F, 70F, 70F (~5F above average).
On the other side of extremes, record high minimum temperatures chronologically are: 70F, 70F, 70F, 69F, 68F, 69F, 70F, 70F (~5F above average).
Record low maximum temperatures chronologically are: 69F, 72F, 71F, 72F, 72F, 74F, 72F, 70F (5-10°F below average).
Precipitation
Orographic lifting is responsible for triggering much of the showers across Hawaii, occurring on the eastern windward slopes. Sea breeze-initiated showers are also possible. The windward upslope regions will receive more precipitation over the course of the year than areas further downslope. For example, according to the LCD for PHTO, an average of 130” occurs near the shore, but just 6 miles inland, the annual average rainfall increases to 300”. Note that PHTO is definitely near the shore.
Chronologically, the daily almanacs show an average rainfall of .42”, .44”, .43”, .42”, .45”, .46”, .46”, and .45” for each of the forecast days, respectively. Chronologically, the record rainfall for each day in the forecast period is: 3.47”, 2.36”, 3.43”, 4.71”, 3.66”, 1.91”, 8.94”, and 7.53”.
