Fire risks in northwestern Hawaii

Northwest Hawaii is fire prone

Much of Northwest Hawaii is dry pastureland, with deep gullies; rainfall at lower elevations can be as little as 4" per year, most of it during the spring's wet season. Pastures dry up during the summer and hot early fall and, if not grazed, provide a ready-made substrate for large-scale wildfires. Global warming aggravates the risks. News articles regularly report on West Coast fires, but the state of Hawaii sees a larger percentage of its area burnt each year than the fire-prone West Coast states.

For more details and maps of fire risks on the Big Island, see [Civil Beat 2022,USDA,HI-DoD-2018].

Wildfires in Hawaii are started by humans

Lightning strikes, which start fires all over the western US, are extremely rare in Hawaii, leaving lava flows as the only natural source of fires. As a result, over 99% of wildfires on the Big Island are started by human activities: cigarette smoking, parking internal combustion vehicles with hot catalytic converters on dried grass, creating sparks by striking metal to rock or metal to metal, using damaged or poorly dimensioned extension cords, setting up fireworks, leaving a BBQ fire unattended, not taking care of composting vegetation, etc. Thus fire prevention is all about paying attention.

Grass fires

Grass fires should not be underestimated: they can burn 12-20ft high and move faster than a human can run, especially downwind, but also uphill and along gullies. Below are some pictures of grassland fires in Hawaii, the last three from the 2021 Mana fire, the largest in the island's history.