The temperatures in Portland, Oregon, could top 100 degrees Fahrenheit (37.8 Celsius) on Tuesday, making it likely the hottest day of a week-long heat wave for the Pacific Northwest region that rarely sees such scorching weather. Forecasters issued an excessive heat warning for parts of Oregon and Washington state. Temperatures could hit the 90s (32 C) in Seattle and 110 F (37.7 Celsius) in eastern parts of Oregon and Washington. While interior parts of the states often experience high temperatures, those kind of hot blasts do not happen nearly as often in Portland and Seattle. “To have five-day stretches or a weeklong stretch above 90 degrees is very, very rare for the Pacific Northwest,” said Vivek Shandas, professor of climate adaptation at Portland State University. As the northwestern U.S. heats up, scorching temperatures in the Northeast are expected to cool in coming days. Read: China floods leave at least 12 dead, thousands evacuated Philadelphia hit 99 degrees (37 Celsius) Sunday before factoring in humidity. Newark, New Jersey, had its fifth consecutive day of 100 degrees or higher, the longest such streak since records began in 1931. Boston also hit 100 degrees, surpassing the previous daily record high of 98 degrees (36.6 Celsius) set in 1933. Residents and officials in the Northwest have been trying to adjust to the likely reality of longer, hotter heat waves following last summer’s deadly “heat dome” weather phenomenon that prompted record temperatures and deaths. In response, the Portland Housing Bureau that oversees city housing policy will require newly constructed subsidized housing to have air conditioning in the future. A new Oregon law will require all new housing built after April 2024 to have air conditioning installed in at least one room. The law already prohibits landlords in most cases from restricting tenants from installing cooling devices in their rental units.