Fire

Wooden settlements and biting cold combine to make fire an everpresent hazard in the towns and villages of Ruslavia, and it is likely that most people will experience two or three major fires in their lifetime. All Izbas are designed in a way that they could be reconstructed within a day, and most major cities have a small number of wood merchants who make comfortable livings providing pre-cut logs needed to quickly rebuild burnt houses.

Type

Natural

Spread of Fire

Unchecked, fire tends to spread both rapidly and unpredictably. Minor factors, such as the dryness of the burning material, the presence of wind or breeze, flammable finish on flooring, dry vegetation in an area, and countless other factors can all contribute to the spread of a fire. Once a fire has burned an area, it will not return to that area. Likewise, once an area has been doused with water or covered with a non-flammable substance, such as dirt, that area is safe from further effects of the blaze for the immediate future. Every round that a fire burns, regardless of whether characters are attempting to control it, roll 1d20 and consult the following table to determine the activity of the fire for that round and how many (if any) 5-foot squares the fire spreads to. The GM chooses which squares a fire spreads into if multiple possibilities exist. Fire cannot spread into areas where it has already been extinguished (unless noted otherwise), nor can it spread into squares where flammable materials are not present. Characters who are inside of a square when it catches fire are subject to damage, as per the rules for catching on fire.
Taken from Pathfinder Rules, and copied here for easy access.

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d20	Fire Reaction
1	The fire does not grow this round.
2	The fire grows 1 square to the north
3	The fire grows 1 square to the east.
4	The fire grows 1 square to the south.
5	The fire grows 1 square to the west.
6	The fire grows 1 square in all directions.
7-8	The fire does not grow this round.
9	The fire grows 2 squares to the north.
10	The fire grows 2 squares to the east.
11	The fire grows 2 squares to the south.
12	The fire grows 2 squares to the west.
13	The fire grows 2 squares in all directions.
14-18	The fire does not grow this round.
19	The fire grows 3 squares in all directions.
20	The fire grows 4 squares in all directions