What effect does moisture have on vegetation with respect to fire?

Moisture plays a crucial role in the flammability of vegetation, primarily acting to decrease it. When vegetation is adequately hydrated, the presence of moisture within plant tissues inhibits the combustion process. Wet vegetation requires significantly more heat to ignite because the moisture content absorbs heat energy that would otherwise be used for combustion.

In essence, when plants are moist, their ability to catch fire and sustain burning is greatly reduced. This is why during times of high humidity and rainfall, the chances of wildfires are typically lower compared to dry conditions where the moisture content in vegetation is minimal. Consequently, as moisture levels rise, the overall flammability of vegetation decreases, making it less susceptible to ignition and spreading of fire.