A heat dome is set to bring stifling temperatures and uncomfortable humidity to the U.S. this week, particularly impacting Nebraska, Illinois, Wisconsin, and Iowa. The heat wave, fueled by moisture from the Gulf of Mexico, will make temperatures feel up to 20 degrees hotter in some areas. The Midwest to the East Coast will experience the first true summertime weather, with temperatures reaching the 90s and overnight lows in the mid-70s Fahrenheit. The heat wave is expected to last into next week, prompting warnings of health risks for those without effective cooling or hydration. Hot and humid conditions can exacerbate pre-existing health conditions and lead to heat stroke, making it important to stay hydrated, minimize sun exposure, and seek air-conditioned spaces.