Studies have identified negative effects of cortisol, a stress hormone, on academic performance. Because natural disasters induce community-wide stress, students who experience natural disasters may subsequently perform worse academically. Our study is the first to examine the immediate effects of close exposure to a natural disaster on academic performance. We examine the impact of the 2017 Pohang earthquake in South Korea on college entrance exam scores. The 5.4 magnitude quake occurred one day before the scheduled nationwide college entrance exam date, necessitating its postponement for one week. Several aftershocks occurred during that postponement period. We find that the earthquake decreased the reading test scores of students in the Pohang area by 0.05 standard deviation but had no effect on math test scores. The reading test was administered earlier in the day than the math test, so these findings suggest that students taking exams in post-traumatic situations might be able to perform better after a warm-up testing period. Finally, male students suffered the largest adverse impacts on their reading test scores, with serious implications given the high-stakes nature of the exams.