As students are exposed to extreme temperatures with ever-increasing frequency, it is important to understand how such exposure affects student learning. In this paper we draw upon detailed student achievement data, combined with high-resolution weather records, to paint a clear portrait of the effect of temperature on student learning across a six-year period for students in Tulsa, Oklahoma. The detailed, longitudinal nature of our data allows us to estimate the effects of both test-day and longer-term temperature on student test performance, and to examine how the effects of both temperature measures vary across seasons, student background, and the distribution of student achievement. Our results show that test-day temperature has no significant effect on student test performance in fall or winter, but a clear negative effect on students' spring performance, particularly in math. Second, we find that summer temperature has a positive, statistically significant, and substantively meaningful effect on student performance on the fall MAP assessment--these effects appear in both math and reading. The results also illustrate that 90-day temperature affects math performance in winter and spring, but these estimates are modest in substantive magnitude.