The k-? turbulence model is adopted in this study to simulate the impact of street canyon AR (Aspect Ratios) on heating within street canyon. The two-dimensional model was validated for RANS (Reynolds Averaged Navier Stokes) and energy transport equations. The validation process confirms that the results of the model for airtemperature and wind speed could be trusted. The application of the said model is carried out to ideal street canyons of ARs (ratio of building-height-to-street-width) from 0.4 to 2 with the same boundary conditions. Notably, street canyon aspect ratio was calculated by varying the street width while keeping the building height constant. Results show that the weighted-average-air-temperature within AR 0.4 was around 0.8% (i.e. 2.4K) higher than that within AR 2.0. Conversely, there was strong correlation (i.e., R2>0.9) between air temperature within the street canyon and street canyon AR. Results demonstrate stronger influence of vertical velocity on heating within street canyon. Evidently, increased vertical velocity decreased the temperatures. Conversely, temperatures were higher along the leeward side of the canyon in lower ARs.