BALTIMORE, MD (June 28, 2019) Due to prolonged heat in the Baltimore region and a heat index expected to reach 100 degrees Fahrenheit Saturday, Baltimore City Health Commissioner Dr. Letitia Dzirasa has issued a Code Red Extreme Heat Alert for tomorrow, Saturday, June 29. The heat index is a measure of air temperature and relative humidity and indicates how hot it feels to the human body. This is Baltimore City’s first Code Red Extreme Heat Alert of the season.