An experimental and theoretical activity has been carried but to investigate the influence of the statistical description of temperature fluctuations on total NO emission predictions in a turbulent gas diffusion flame. A small cylindrical combustor has been simulated, using a commercial CFD code describing flow and combustion processes, integrated with a decoupled NO kinetics model that solves the transport equation of the average NO mass fraction. From the comparison of the computed results with in-flame measurements of temperature and species concentrations it can be concluded that modelling of the temperature variance transport equation is required to obtain correct NO predictions, and that results are sensitive to how the combustion contribution to the variance source term is handled.