Climate change and its worldwide effect on temperature is a well-documented phenomenon. As with much of Canada's transportation infrastructure, reinforced concrete bridge girders experience the effects of these changes. Inconsistent heating of bridge girder cross-sections results in large nonlinear temperature gradients. However, bridge design codes and specifications rely on historical climate data to inform design requirements. Furthermore, the location should be considered when determining temperature distributions due to the wide variations in climatic conditions in Canada. However, the Canadian Highway Bridge Design Code (CHBDC) specifications provide a fixed thermal gradient profile without considering the variation in the Canadian climatic regions. In this study, the temperature distributions, variations, and gradients were investigated for a concrete box girder for different Canadian climate regions. Two separate one-month transient thermal finite element models were developed for each representative city of the climate regions to develop the concrete girder's temperature behaviors and distributions. The results showed that the daily maximum mean temperatures and the extreme daily positive thermal gradients do not coincide. The predicted maximum mean temperatures were higher than the CHBDC maximum mean temperatures of the concrete box girder for the selected cities. Comparisons between the proposed thermal gradient profiles, values, and patterns with the CHBDC thermal gradient specifications were conducted. The comparisons showed that one fixed thermal gradient profile is inadequate to cover the variation in the thermal gradients and differentials of the Canadian climate regions.