If you know what you're doing, have backup power, and some water storage, someone staying behind to deal with the spot fires before they grow can have a large impact on the survivability of a house or neighborhood. If you're somewhere prone to wildfires and you have a pool (and are the sort to stay behind...), a good propane powered pump and enough hose to run good lines around the house will have a huge impact - and even if you don't have that, a few thousand gallons of water storage isn't that expensive (compared to a house). If you've got a properly set up wildfire rated house without much debris around it, a good Class A rated roof, and some water, you can do a lot.
Of course, you can always roll a 1, and certain houses (shake roof) will simply go up like a candle in an ember storm like this, but in that situation, I'm not sure a car stuck in traffic is the better option.
Houses can handle an awful lot of radiant heat, and they'll survive perfectly fine a radiant heat flux far beyond what a human can tolerate. You just can't let direct flame impinge on them for very long before it spreads.
Locally, a combination of stucco and concrete tile roofs can make a house basically immune to fire rain--but concrete tile roofs are not an option in most places.
(It also helps that bush properties have large water tanks attached to them)
Check Class A roof tests. A lot of asphalt shingles, properly installed, actually are Class A fire rated - which is a 12x12 2kg grid.
https://www.builddirect.com/learning-center/building-materia...
Interior corners on the roof or house tend to cause problems, though. Debris builds up and ignites, and just impinges on the siding until you light something behind it.
You can also have firebrands entering through attic vents and bypassing the roof - there are vent types that are resistant to this, but tend to cost a good bit more.
Why we don't do this in urban wildland interfaces... no idea.
I’m using guesstimates for humidity and wind speed based on the spotty data available from the local government website. Also just totally fudging the fuel load number.
I’m reading spotting distances between 1.5 and 2km.
Overall FFDI of 41 so a bad day but not extreme by our standards. Would have been a lot worse with lower humidity.
They don’t throw embers like a crowning bushfire, though.
If you look at the aftermath, you're almost certain to see buildings mostly burned from the top down, with intact landscaping around them - that's a strong sign that the spread was firebrand based.
Unfortunately, if you've not built for it ahead of time (and sometimes even if you have), there's literally nothing you can do when the fire hits in high winds.
I mostly deal with grass fires locally, and even those can get going in a hurry with a strong wind. Of course, the only days they ever seem to burn is in a strong wind...