Total dry matter, number of tillers/plant, leaf area index and grain weight were evaluated through time, in wheat seeded at different dates. Thermal time and the absorbed radiation by the crop, were calculated with data from a metereological station, located near the experimento Results suggest that higher temperatures in late sowing dates, can reduce the number of tillers/plant and leaf area index, by shortening the period of growth before anthesis. Also, in late sowing dates, total dry matter and number of kernels/m2 were reduced. Both parameters were closely related to the absorbed radiation by the crop during preanthesis. The reduction of the grain growth period duration after anthesis, due to higher temperatures in late sowing dates, decreased grain weight. It was concluded that the interaction between temperature and solar radiation, could explain the decrease in production of spring wheat with late sowing dates, in the irrigated plain of central Chile.