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A hazard of being in or near a forest, at some times and places (as is being unfortunately observed in Canada and Siberia at the moment), is fires.

How far from the trees do you have to be, to be safe from a forest fire?

To be specific, say:

  • You are in a tent in the center of a circular clearing surrounded by forest.
  • There is a lot of understory litter, deadwood, enough that if the forest does go up, it's likely to be a crown fire, the most dangerous kind.

How large a clear radius would be needed before you can survive the smoke and superheated air? I get the impression even being a hundred meters away is not safe; is that correct? How about a kilometer away?

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    Agreed. For example, in Lytton, the wind was reportedly about 70km/h before the fire. That would result in very different survivability than the same locale at with less wind. Then you would have to indicate the clearing situation - at this moment, most grass in that area is probably flammable as well and not all that short. Probably better off reading up particulars of wildfire incidents and who survived and who did not. Jul 4 at 1:04
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    It’s an open-ended enough question that might serve you better on Worldbuilding (which I see you’re a member of). As the author, you also have leeway in finding reasonable caveats to make things survivable for your intrepid heroes. For example, some sort of cave or mine tunnel could make things survivable but while less practical as an answer for Outdoors, would be a valid choice as an author. Plus, it allows you to leave someone outside to die, or have someone reach safety but die due to the fumes anyway (37/42 in the group there lived). Jul 4 at 2:40
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    Will also depend on the vegetation type - check out Eucalyptus forest fires in Australia creating their own weather systems and fire storms travelling at <80 mph.
    – bob1
    Jul 4 at 9:09
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    Radius is the wrong way of thinking about it half a mile upwind is very different to half a mile downwind, is very different to half a mile away the other side of a long lake that lies parallel to the wind. But note that the convection from a fire causes its own local wind feeding air to the flames, so I'm talking about the larger-scale winds
    – Chris H
    Jul 5 at 9:28
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    Some look at ground scrub and say "well that's not a forest, so it's not subject to forest fires". That's why we call them "wildfires" now. If the forest is dry enough to burn, so is the scrub. Jul 5 at 19:18
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Miles.

But it depends.

I was at Grande Marais rapids on the Churchill River. We'd carried the canoes over, but stopped for lunch on the uphill end, as the lower end was swamp and bugs. When we stopped for lunch we could see the smoke some 5-8 miles away, judging from the water bomber activity. Over the course of a leisurely lunch the wind shifted, the sun went copper coloured, then gone, and ash began to fall.

We packed up lunch, finished the portage and were on the water in another 20 minutes. As we finished packing, ash had changed to dead cinders. As we started paddling, some of the cinders were burning coals. A few kids had minor burns when they landed on skin, and it burned holes in the covering of a few life jackets. (A short water fight got everyone wet enough to quench sparks.)

From talking to a fire guy later, the portage burned down about 4 hours later.

We changed our route four times that trip. On a canoe trip in the Churchill River system this is reasonable and safe to do. The main river is mostly a chain of lakes. Tributary rivers like the Reindeer, Foster, Davin are also good sized, with frequent multi kilometer sized lakes. Any time two lakes are within a km of each other, there is probably a portage between them. We had a strong group and 40-60 km days were routine. (Not counting portages) It's fairly easy to put substantial amounts of water between you and the current fire front.

We made a point of camping on islands, and, on larger islands, using the upwind end.

We were in daily radio contact (sat phone) with our support station to track the fire's locations.

At one point we were paddling through a section where the fire had been. One shore was still burning, albeit somewhat fitfully. Ground fires were working the bits that the crown fire had skipped. Occasionally a tree would torch, and we'd feel a flash of heat from 100 yards away.

That said:

  • While crown fires can move very fast, most of the time fires move slowly.
  • The biggest issue in traveling near fires is the smoke. It's irritates the lungs when doing strenuous activity, irritating to eyes, and it decreases visibility. The sun can vanish in haze, and without a compass it's easy to get disoriented. Much of the time visibility was limited to 1-2 km. We had whole days when the world was reduced to being inside a ping pong ball, with a shoreline on one edge. Non-GPS navigation was challenging. (I would get out the GPS only when confused, or at meal stops just to verify...) We ended the trip early at the community of Brabant Lake, about 1.5 hours north of Missinippe. The road was being run in one-way mode with pilot vehicles, because visibility was under 100 yards.

I did a trip in Willmore Wilderness (Alberta, BC border, north of Jasper Park) when BC was burning up. While the fires were never within 100 miles of us, the sun was burnished copper the entire trip, and the view from the passes ranged from indistinct to being inside a ping pong ball.

I had an InReach device, and exchanged texts with my outside contact twice daily for fire news. Our plan was to exit the park if fires got within 25 miles. Our route was planned so that the trailhead was at no point more than two hard days from our location.


Flip side: Often a forest fire will just be a ground fire that moves slower than a slow walk. This sort of fire can be fought with a shovel and pulaski, with fire fighters right on the fire front. Don't be fooled: Even with good communications, planes watching the fire, and professionals, the fires can blow up, and men die.


If you make a mistake and are caught:

  • Move your route to existing firebreaks: roads, ridge tops, gravel flats, wide creek valleys, swamps, above grass line in mountain country.
  • Try to remain situationally aware. With reduced visibility this is hard. Monitor wind direction, amount of smoke
  • Move as fast as you can to the trailhead, but this is a marathon, not a sprint.
  • Have an alternative plan if the fire gets by you or if there are multiple fires in your area.
  • Unless running for your life try to avoid traveling at night. It's exhausting, and easy to become immobilized by a fall or mis-step. If you are on a road, by all means, travel at night. It's cooler and you are probably too nervous to sleep anyway.
  • Cache as much gear as you can to travel lighter and faster. You can come back for it later. Your $5K 8 kg camera setup won't do your roasted corpse any good at all.
  • Fill your water bottles at every opportunity.
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There is no safe distance that can be cited. Encountering a forest fire while on a leisure activity should be considered an emergency and mandate immediate exit in the quickest direction away from a fire. Any other course of action puts yourself and rescuers in unnecessary danger.

Use your best judgement.


Given regular and reliable updates and telemetry about conditions, fire breaks, and fire evolution as well as good maps and support for quick evacuation, some safe distance (several air miles) from the nearest hot spot provides a buffer.

As an empirical example justifying the several mile status, from time to time the PCT is rerouted around fires and this is usually a 10-20 mile, well coordinated detour. Sometimes it is not possible

https://www.pcta.org/discover-the-trail/closures/southern-california/bobcat-fire-angeles-national-forest/

enter image description here

Source: Pacific Crest Trail Association

Anyone entering terrain where you anticipate unexpected fire should probably carry an emergency fire shelter. In the case that you are caught by surprise you might have a chance.

https://www.fireapparatusmagazine.com/content/dam/fa/print-articles/volume-23/issue-9/1809FA-petrilloshelter-p08.jpg

Source: fire apparatus magazine

Now, this might look cozy but they are basically human baked potatoes.

https://cdn.theatlantic.com/thumbor/YhCS23wuUH63gpWBiRPuVsf7-AM=/177x171:1085x682/720x405/media/img/mt/2014/05/fire_shelter_pics2/original.jpg

Source: The Atlantic

https://www.nasa.gov/sites/default/files/styles/full_width/public/thumbnails/image/tepee-fire-shelter-11-29-1963.jpg?itok=V57dyeJQ

Source: NASA

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