A heat dome happens when a region experiences prolonged high pressure that traps heat. This phenomenon can cover a large area, extending across multiple states for days or even weeks. Underneath the heat dome, people, crops, and animals suffer from the oppressive, stagnant heat that feels like an oven. Heat domes are closely linked to the behavior of the jet stream, which is a band of strong winds at high altitudes that usually flows from west to east. Normally, the jet stream follows a wavy pattern, oscillating between northern and southern directions. However, when these waves become more pronounced, moving slower and sometimes becoming stationary, heat domes can form. The air piles up and sinks as the jet stream swings farther north, leading to warming air and clear skies due to decreased humidity. This allows the sun to intensify the heat near the ground. If the descending air passes over mountains, it can become even warmer. The 2021 heat dome event led to record temperatures in Washington and British Columbia, with 120 degrees Fahrenheit (49 degrees Celsius) and 121 degrees Fahrenheit, respectively. Heat domes typically persist in one area for several days, but they can last longer or move, affecting neighboring regions. In rare instances, they can persist for extended periods, such as the deadly heat wave in the southern Plains in 1980, where thousands of people lost their lives. The Dust Bowl years of the 1930s also saw the widespread impact of heat domes across the United States. Heat domes have serious consequences for humans due to the stagnant weather conditions they create, which result in weak winds and increased humidity. These factors make the heat feel even more intense and perilous, as the body’s cooling mechanism through sweating is less effective. The heat index, which measures the combined impact of heat and humidity, is often used to indicate how it would feel to most individuals. High humidity also limits cooling at night, making it difficult for individuals without air conditioning to find relief and increasing the risk of heat-related illnesses and deaths. Furthermore, with global warming, temperatures are already higher, exacerbating the impact of heat domes. One notable instance occurred in 1995 when an estimated 739 people died over five days in the Chicago area due to a heat dome with high temperatures and humidity. Overall, heat domes are significant weather events that have far-reaching effects, and understanding their mechanisms can help mitigate their harmful impacts.