cultivation of spring wheat varieties has expanded into northern areas where it is an integral part of the crop rotations followed by the farmers. around thunder bay, in northern ontario, spring wheat is typically grown from may until september. crop success or failure depends on critical stages of growth in spring wheat that include emergence and tillering (in may-june), stem elongation (jointing) and booting (in june-july), spike emergence, heading (mid july), anthesis, grain filling (july-august), and kernel hardening or maturity (in august). weather plays a vital role at each of these stages. here, analysis is presented of the role of weather during seeding, tillering, jointing, grain-filling and kernel-hardening stages on the grain yield of spring wheat (cultivar sable) from 2003-2017 at the 阿根廷vs墨西哥竞猜 agricultural research station (luars), thunder bay. the analysis was conducted using the crop-sim ceres model and weather records at the thunder bay airport (~10 km from luars). simulation of future yields followed with projected climate according to the representative concentration pathway (rcp) 2.6, a greenhouse gas trajectory adopted by the intergovernmental panel on climate change (ipcc). the simulation predicted an average 26% lower grain yield by 2030. sable grain yield was correlated to maximum (r2 = 0.69) and minimum (r2 = 0.46) temperature, but rainfall was not a factor that could predict wheat grain yield on its own. in the future, growers could experience a greater number of heat-stress days, and an increase in minimum temperatures during the jointing, grain filling and kernel-hardening stages that may limit future yields.