(Portland, OR) -- Portland is preparing for its second major heat wave of the summer, with temperatures expected to climb near 100 degrees starting Friday. An excessive heat watch is in effect through the weekend, though Multnomah County has not yet decided whether to open cooling shelters. Officials encourage residents to use libraries, community centers, splash pads, and public fountains to stay safe. Water misting stations are also open across the city as health officials warn of the risks of heat-related illness.