When talking about warming, it is natural to focus on the daytime high temperatures. However, climate change is also occurring at night and we see some of the strongest climate signals in these low temperatures. Elevated nighttime temperatures, especially during the summer, can create uncomfortable conditions and limit opportunities for people to cool down. Nighttime heat poses a health risk, especially for vulnerable populations such as the sick, elderly, and lower-income communities who may not have air conditioning. For people with air conditioning, elevated nighttime temperatures increases their utility bills.