August 11, 2023

The Origin of the Hawaii Fires/Preventing a Similar Tragedy in the Future

The terrible fires around Lahaina, Maui have resulted in a death toll of 67 (which will certainly rise) and an economic loss of billions of dollars.

We can take steps to prevent this from happening again, including understanding why this event occurred and building the observation, warning, and action infrastructure as California.

Why did this event occur?

The origin of this disaster is now becoming clear:  massive amounts of dry, dead fuel (mainly grass), strong downslope winds produced by strong trades interacting with local mountains, and human ignition, most probably from powerlines.

Dry grass and shrubs

Maui was a tinderbox ready to burn explosively.  As noted in a number of articles and Hawaiian government websites, a large portion of Hawaii is covered by highly flammable, invasive, non-native grasses.

Flying into Maui in late June.  
Dry grass everywhere (looking north along the West Coast of Maui)

Western Maui is typically wet in the winter and quite dry (and warm) during summer (see plot for a station near and north of Lahaina).  Grass grows during the winter and then dies/cures during the summer, leaving brown desiccated grass.  This is not climate change...this is the normal situation.

This year the winter was particularly wet, enhancing Maui grass volume,  followed by a dry summer.  A huge supply of dead fuel was ready to burn.

There has been a lot of talk in the media about drought and even "flash drought" driven by climate change (see Seattle Times headline below).  This is all silly and irrelevant.  The opposite of drought last winter resulted in lots of grass and even a normal summer would have resulted in the grass ready to burn now.  

Also important is that the grasses are  1-10hr fuels that dry within hours under the proper conditions (low relative humidity, winds, sun).  The conditions earlier this week were optimal for drying with warm, dry, downslope flow.  The grasses could have been drenched a few days before and burned under such conditions.  Climate change is irrelevant in this situation.

The Winds

Lahaina was hit by powerful winds, with gusts exceeding 60 mph.   Winds that provided oxygen to the fires, pushed the fire quickly forward, and downed powerlines, helping spark the fires.  

There is a lot of talk about the winds coming from hurricane Dora, which passed 800 km to the south of Hawaii (see satellite image below).  

The winds that hit Lahaina were NOT hurricane winds.

The winds that helped destroy Lahaina were caused by strong trade winds, produced mainly by enhanced high pressure to the north, interacting with Maui terrain to produce strong/dry downslope winds.  

These were localized strong winds that amazingly were well predicted by the NOAA HRRR model and others.

Hurricane Dora was a small storm that passed well south of Hawaii. The strong winds of the hurricane did not significantly affect Hawaii as some claim.

NOAA map of the path of strong winds from Hurricane Dora

During the last day UW Research Scientist David Ovens, a member of my research group, ran the WRF weather prediction model at high resolution for this case.

The results are stunning.  Below is the 27h forecast of wind gusts at 8 PM PDT on Tuesday, Aug. 8th.  Gusts to around 65 knots (75 mph)  around Lahaina  (color shading).  Pressure is also shown as are the wind vectors.  A life-threatening prediction.

Moderate winds approached the mountains of West Maui and then accelerated down the western slopes of the terrain.  A stable near crest level assisted.

Strong winds were also observed over central Maui west of Haleakala volcano:  more grassfires occurred there.

Let me repeat:  these were NOT hurricane winds but local downslope wind accelerations, produced by the occurrence of perfect meteorological conditions, something I will review in a future blog.

An analog to such wind acceleration is the strong winds that can occur in Enumclaw, Black Diamond, and North Bend, Washington under strong easterly (from the east) flow.


Although little information has been forthcoming on this point, the ignition had to be human-caused, since there was no lightning in the area.  Considering the massive wind damage to electric infrastructure, with reports of fallen and sparking powerlines,  it is quite probable that the strong winds caused the ignitions that started the fires.

We Can Make Sure This Never Happens Again

First,  it is essential the actual causes of the fire be understood (extensive dry grass, strong local winds), not climate change and "flash droughts."   Only a science-based, rigorous understanding of the wildfire's origins can lead to a better outcome in the future.  Incorrect, politized explanations work directly against solving the problem.

Second, many more wind observations are needed.  The weather observing network on Maui and particularly western Maui is totally inadequate, as shown by the map below. 

Virtually no wind observations around Lahaina.  Unbelievable.  Weather observations are critical for understanding the wind threat, to warn the population.  Wind observations foster decisions to de-energize powerlines to prevent ignitions.

California has learned this lesson and has installed thousands of weather observation sites.  Hawaii needs hundreds.

Third, much better use of weather forecast models for warning and decision-making is required.  As shown above, current weather prediction technology is so good that most localized wind threats can be forecast well in advance.

The National Weather Service waited way too long to put out a  Red Flag Warning for all leeward areas of the Hawaiian Islands on August 7th, the day before.   And with the intense winds predicted by the NOAA HRRR model, MUCH more severe warnings should have been made for the Lahaina area.  NOAA and the State of Hawaii need to work out a comprehensive plan for better warning of such dire threats to life and property.

 Powerline De-energization

Hawaii electric utilities should immediately make plans to turn off the power to threatened areas when strong winds are either observed or predicted.  California and Northwest utilities have already begun this life and pre

The combination of rigorous science, more observations, better use of models, stronger and more aggressive warnings, and powerline de-energization can ensure that a tragedy like this week will never occur again in the Hawaiian Islands.


  1. The lessons of the 2018 fire which destroyed Paradise in California should be plainly evident to anyone who is assigned responsibility for being proactive in dealing with the threat of wildfires wherever these might occur.

    It has been clear for at least a day now that local civil authorities in Hawaii are completely culpable for not recognizing that a seriously dangerous situation was developing on Maui before the fire ignited, and for not taking immediate action to deal proactively with the danger of wildfire by shutting off power to the island's transmission lines well before strong winds could take them down.

    1. I was thinking the same thing. I evacuated from Paradise, the morning of the Camp Fire so I have first hand experience of how terrifying it is to be confronted by these kinds of firestorms. It's disappointing to see that the lessons learned from earlier fires aren't being applied today. This is resulting in many unnecessary deaths and destruction.

  2. Aside from CA, the NW and Hawaii, are there any other parts of the US which might benefit from such a system, but lack it as present?

  3. "Incorrect, politized explanations work directly against solving the problem." Great point as always, but the real agenda from the Climate Doomsayers is that actual and objective research is not allowed, unless it reaches their own biased conclusions. Until we achieve real scientific inquiry once again in this country (and in the world), yeoman efforts from you and your colleagues are destined to be disregarded.

  4. Is it worth commenting on this paper on "drought"?$002fclim$002f35$002f13$002fJCLI-D-21-0754.1.xml?t:ac=journals%24002fclim%24002f35%24002f13%24002fJCLI-D-21-0754.1.xml&utm_medium=email&utm_source=substack

  5. Living at the edge of the forested Cascades, I often wonder how well-prepared the agencies are these days. Decades ago, logging was significantly curtailed in the Mt Baker Snoqualmie National Forest, something that was a heart-breaker for many of us in the mountains on multiple counts. The foresters' interest was in keeping the woods healthy, and they harvested the resource "in rotation." The proceeds supported trail crews, fire crews, and forest road maintenance; forest roads are essential for fire-fighting, heaven forbid something (or somebody) sparks a fire near here. The "city folks" who come up in droves worry me far more than the weather, including lightening.

    1. Look at the bolt Creek incident from last year for your answer

  6. What do you think of the claims in That article blames climate change for the fires for several specific reasons:

    - Drought. It says climate change has resulted in weaker El Ninas, thinner clouds, and more northerly storm tracks -- all leading to less precipitation in both winter and summer. (I realize you say that this winter was unusually wet and that made the fires worse).

    - Vegetation changes. It says wildfires have destroyed native vegetation while drought has destroyed sugar cane farms, to be replaced by invasive grasses that are prone to burning.

    - Winds. It says that increasing air and ocean temperatures are leading to stronger storms.

    You present non-climate explanations for the fires that seem to make sense, while dismissing climate factors. This NYT article presents climate explanations that seem to make sense, while ignoring non-climate factors. Could both be true?

    1. Most of that article is simply and demonstrable wrong. Excessive precipitation produced more grass. Drought was not an issue for these fires, which occurred on the dry side of the island in grass that dries in hours even after saturated. The ocean temperature business is not relevant to the cause of the strong winds. Importantly, the sea surface temperatures were COLDER than normal near and east of this is all nonsense. Very poor journalism. Embarrassing really.

    2. Barry Bateman, farmer with a B.Sc. Advanced (biology). The NYT on CO2 related climate - naive, short sighted, purporting to love the environment while remaining entirely uninformed of CO2's foundational role. Good article, Cliff Mass! The grass was not only made thicker by more rain but by more CO2. CO2 is as important as water for our carbon based life on Earth. More of it makes everything grow better and greener. Our natural climate moves in long cycles, not the thirty years imagined by the NYT. We have been warming (about 4°C so far) since the "Little Ice Age" of the 1600s. see Dr. Judith Curry on "Eddy cycles".

  7. Thank you for this great explanation. Two things that are particularly irksome are 1) the fact that the cause of fires these days is rarely made known. If it is it is way past the fact and at the very end of some obscure article. If these fires are being caused by humans it would be helpful for everyone to know that so we they can be mitigated; 2) since fire seem to be occurring more frequently, it just seems like it would make the most sense for a variety of agencies and people to be working to prevent these things instead of wasting their time on some of the other things they are fiddling around with.

    1. The cause is rarely made known? I just googled the Sourdough Fire as an example, and the cause was prominently stated (lightning) in the first search result (the Seattle Times). Of course for many fires the cause is unknown and unknowable. To some extent it doesn't matter since ignition sources in many places are inevitable and the important thing is what happens next -- does the fire go out in a minute or spread for a month?

      I regularly hear of various mitigation measures in fire-prone times and places involving campfires, power lines, vehicles, etc. Perhaps more should be done but what sort of "fiddling around" do you think agencies should stop doing?

    2. The New York Times admits openly that they bias everything to support political narratives. The terrible consequences of burning fossil fuels is one such meme. You can find this quite conclusively proven by Bari Weiss in her resignation letter. Search for Weiss resignation letter.

    3. "Admitted openly"? Where?

      And no, the resignation letter of a disgruntled employee is not "conclusive proof" of anything. It's known as an assertion.

      (I try to keep my comments to science rather than politics here, but since your entirely political comment has been approved, I guess this reply is on-topic.)

    4. Bari Weiss is not a conservative and you obviously haven't read the letter. What she alleges is a hostile workplace where harassment is rampant and based on viewpoint discrimination. There is lots of other evidence such as the firing of the editor who ran an editorial by a US Senator, Tom Cotton.
      This is the same Times that won a Pulitzer for a fabricated story about Russian collusion with Trump. They ran literally hundreds of stories about this fabricated story and have not retracted a single one. But I guess perhaps you also haven't read the Durham report either.
      Denial isn't a phenomenon that is limited to climate science - you are proof of that.

  8. Is proactive burning when the grass isn't that dry in earlier season a good idea? Or even just mowing down large patches of the grass an good option?

    1. With fine fuels like this by time they are ready they can go quickly even if a little green and the fire can quickly dry grass our ahead of it. Mowing is an idea while green, but better yet, using animals grazing. They remove grass and we get protein. Areas are trying goats. Here where I am at in central Washington we have a saying, log it, graze it, or watch it burn. However, here to have cattle in some of these areas is so ridiculous. Have to be wary of cows stepping into water shed where bull trout might be. Also, most green initiative people do not like cattle as they are major contributor to green house gasses. However it truly is beneficial to our forest lands. I believe offsets their carbon footprint for sure.

  9. For some reason the movie Jaws comes to mind, where they knew of the threat, but didn't want to disrupt the revenue stream from the tourists so kept it quiet.

  10. We need to nationalize the oil corporations and use the profits on the climate emergency so trajedies like this don't continue. Typical myopic view Cliff!

    1. I would laugh except you are a true believer. The government nationalised oil in Venezuela, how's that working for them?

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  12. Since there was a lack of weather stations on West side of the island. The only weather stations where ones monitored by private citizens. There are many questions to be answered. What where the dew points, what was the air temperature. Wind speed. A rule of thumb when you have down sloping winds the air temperature increases 5 F. ever 1000 feet of decent. So if the air temperature at 5,000 feet was 70 F. at sea level it would 95 F plus. I myself am a avid skier and a commercial fishermen. So I am very in tune with the weather. What happen in Lahaina was a non natural event.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

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