Anthropogenic climate change presents a potential threat to maple syrup production in Canada. To mitigate risks associated with climate change, information about the biological changes that may occur in a warming climate are necessary. This project studied one component- sap flow- that in part determines the economic viability of maple syrup production. A temperature-based sap flow model was used to project the start of the sap flow season in southern Ontario, and GIS applications were used to aggregate the results. The start of the sap flow season was projected for early, mid, and late-century periods under two climate change scenarios, RCP4.5 and RCP 8.5, using data from the Canadian Regional Climate Model (CRCM) CORDEX experiments. In both scenarios, a majority of the study area experienced an earlier start to sap flow; the northernmost extent of the sugar maple range saw the greatest shift to earlier sap flow dates, particularly in the RCP8.5 scenario. Some areas around the Great Lakes did not meet the criteria for sap flow to begin for the mid-century and late-century periods in both scenarios. For the mid-century period, the RCP4.5 scenario showed sap flow beginning earlier for most of the province- excluding the northernmost areas- than RCP8.5. For the late-century period, RCP8.5 showed a greater shift in sap flow dates than RCP4.5. The results suggest that maple syrup producers will need to take adaptive measures to respond to shifts in the sap flow season