The emergence of the SARS-CoV-2 pandemic has caused tremendous upheaval throughout the world, leading to extensive efforts to reduce transmission of the virus and cases of the disease it causes, COVID-19, resulting in significant economic disruption. Since warmer weather is known to decrease the transmission of other coronaviruses, researchers at the University of Louisville’s Christina Lee Brown Envirome Institute, the Johns Hopkins University School of Medicine and the U.S. Department of Defense Joint Artificial Intelligence Center theorized that atmospheric temperature also would affect transmission of SARS-CoV-2. To find out, they compared temperature data and logged cases of COVID-19 in 50 countries in the Northern Hemisphere between Jan. 22 and April 6.