First and Last Frost Dates (IMAGE) University of Utah Caption This image shows the average day of the year with the last spring frost (left) and first fall frost (right). Cooler colors indicate an earlier day of the year. Credit Courtesy of Court Strong/University of Utah. Usage Restrictions Credit Court Strong License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.