Cities: Skylines - Remastered

When setting up your game, make sure to have Disasters turned on. Having the frequency turned to maximum will increase your chance of getting this.
Forest fires do not spawn in if there is not a sufficiently dense area of trees in the land owned by your city; you can use the tree placer to place down a bunch of trees near each other to increase the chance of a fire starting.
When placing trees, a click right or left on the d-pad will increase the tree painter brush size, whilst up/down changes strength, allowing you to easily place many trees in an area by increasing the size and strength of the brush.
Simply wait until a fire breaks out and this achievement will unlock.