How do fires affect the weather?

Fire impacts on weather

The impacts of wildfire on weather are, unsurprisingly, very complex. This is due both to the number of variables involved (fire size, fire intensity, terrain, background weather conditions, etc.) and to the interactive nature of the fire-weather relationship - at any given moment the weather is changing the fire while the fire is changing the weather.

At its most simplistic, we can say that a large, hot fire can generally be expected to heat air near the ground surface, causing it to rise. This creates a convection column of rising air, which may in some instances carry smoke and embers thousands of feet up into the atmosphere (convection columns can exceed 25,000 feet in height). Surface air rushing in to replace the air that is rising creates strong indrafts - local winds that in turn may intensify and spread the fire. This positive feedback between fire, convection, and winds explains why large wildfires are often said to "create their own weather."

One of the byproducts of combustion is water vapor. As the convection column rises and (slightly) cools that vapor may condense, releasing latent heat into the column and thereby reinforcing the convection. This is similar to what happens in a convective thunderstorm, and indeed lightning, rain and downbursts are sometimes generated, just as in conventional thunderstorms. Such downbursts can, in turn, accelerate the spread of the fire in a dangerously rapid and unpredictable manner.

Other contributors said...

• Fires affect the weather when the smoke gets in the air and if there are any chemicals in it, it could make acid rain.
• Makes the weather feel very hot.

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