Boston is experiencing its third heat wave of the summer, with temperatures reaching the low to mid-90s inland and cooler conditions near the coast due to sea breezes. The city has declared a heat emergency from Monday through Wednesday, as announced by Mayor Michelle Wu. The heat wave is accompanied by increasing humidity midweek, with dew points rising into the tropical range by Thursday ahead of an approaching cold front. This front is expected to bring scattered thunderstorms and cooler temperatures by Friday, ending the heat wave. Air quality is moderate due to ozone, and a thin haze from distant wildfire smoke has been observed. The heat emergency aims to address the impacts of this prolonged period of high temperatures, which are approximately 17 degrees Celsius above normal for the region.