Jisung Park did a remarkable study on the impact that heat has on academic performance:

• Data indicates that if on the day of an exam, temperatures are as high as 32 degrees Celsius, then students will score 4.5% less on their exams.
• Having a school year with five more hot days than normal, causes students in that classroom to lose $37,000 in lifetime earnings.
• All of this is particularly concerning since in cities such as New York, fewer than 62% of classrooms have air conditioning.

Read the full Harvard summary here.

Via: Marginal Revolution