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Climate in Hilo

Paradise awaits! However there are some realities about our tropical island you may want to know about before you come...

Rainfall

Bear in mind according to U.S. Climate Data :

  • Hilo has an average 126.69 inches of rainfall a year
  • Seattle has an average of 37.13 inches of rainfall a year

When it rains, it pours. Peaking in March and November, Hilo receives 13-15 inches of precipitation in those months. Granted it dumps like a water bucket and moves on to sunshine, but bring a waterproof-yet-light-jacket, and a decent size umbrella.

Humidity

Being classified as a Humid Tropical Climate...it is wonderful for the lungs and pores, not so wonderful for those who consistently style their hair.

Bear in mind there is a fairly consistent ocean breeze which is a wonderful deterrent to feeling overly sticky, however directly after rain a fair amount of that liquid re-evaporates and makes life muggy for an hour or so.

This element will mold and rot clothes, leather, left behind dishes, and many other surfaces which you wouldn't expect. Staying on top of laundry or other such chores is more important than in other locations as you may be in for a putrid surprise.

Temperature

A wonderful thing about Hilo is its very narrow range of temperature.

In December the lowest average is 65°F/18°C, and in the height of the July it’s around 83°F/28°C. Due to this limited range, most homes deem air conditioning an expensive luxury, if they have it at all. And central heating simply does not exist in Hilo.

Bear in mind this is not the same throughout the island.

For instance, on the Kona side of the island it can get up into the 90s, whereas Hawaiʻi Volcanoes National Park lows in winter get down to the 49°F/9°C range and Mauna Kea is capable of snow. When most houses lack central air conditioning or heat this can pose a challenge.

Vog

Wikipedia defines Vog as:

"A form of air pollution that results when sulfur dioxide and other gases and particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. The word is a portmanteau of the words 'volcanic', 'smog', and 'fog'."

Aerial photo of a lava flow meeting the ocean creating a plume of steam
An active lava flow meets the ocean

Basically the volcano is always active as we are still over the hotspot. When it hits the air it releases gas which is not friendly to asthma and other breathing conditions.

Hilo bay with clear skies
Hilo on a clear day
Hilo bay with settled vog reducing visibility
Hilo on a voggy day

Vog can be seen in the comparison between two photos from Coconut Island area looking back toward Mauna Kea.