Quoted from: https://www.openwfm.org/wiki/WRF-Fire 

WRF-Fire combines the Weather Research and Forecasting model (WRF) with a fire code implementing a surface fire behavior model, called SFIRE, based on semi-empirical formulas calculate the rate of spread of the fire line (the interface between burning and unignited fuel) based on fuel properties, wind velocities from WRF, and terrain slope. The fire spread is implemented by the level set method. The heat release from the fire line as well as post-frontal heat release feeds back into WRF dynamics, affecting the simulated weather in the vicinity of the fire. The fire code is written in Fortran 90 following WRF coding conventions. It is integrated as a physics option, called from WRF as a subroutine. It calls WRF libraries for utilities such as I/O and communication between MPI processes. The fire code executes on a part of the domain, called a tile (in WRF nomenclature). All communication between the tiles is in the caller; thus, one time step requires multiple calls to WRF-Fire.

WRF-Fire is essentially a reimplementation of CAWFE with the weather model replaced by WRF and with the fire spread implemented by the level set method in SFIRE. The subroutines for the computation of the rate of spread and for the insertion of the heat flux to the atmosphere are taken from CAWFE.