"You don't need a weatherman to know which way the wind blows," Bob Dylan once sang. And right now, for much of the country, those winds are blowing hot and hotter, thanks to climate change. Records are being set not just in Death Valley but in the Northwest, where nearly 200 people died in the recent unprecedented heat wave. Highways buckled and residents of cities accustomed to cool summer days and foggy mornings stripped store shelves of air conditioners and fans. Washington state and Oregon have been particularly hard hit, but the suffering has extended to the central Rockies into southern Canada. This week's heat wave was the fourth in the past five weeks. Forecasters describe what is happening out west as a "heat dome" — an event that is expected to go on for days. With the heat — combined with drought and overdeveloped wildlands — has come an unprecedented number of wildfires. As of Monday, 80 fires were burning in 13 Western states, according to the National Interagency Fire Center. Even in the greater Boston area, where June is often a cool-ish prelude for a far balmier summer, a record heat wave forced some schools to close and many communities to declare heat emergencies. This year's was the hottest June ever recorded in Boston's history. All this heat is a threat to public health and safety. At least 700 people die of heat-related causes each year in the United States, and tens of thousands more get ill — a toll expected to rise. It's past time to battle heat waves like the lethal hazards they are. "Record high temperatures are occurring more frequently in the United States, and climate change is causing heat waves to become more intense, directly impacting human health, including heat-related illnesses and deaths," noted a paper published last week by the Centers for Disease Control and Prevention that looked at the current impact of the climate crisis. The study analyzed heat-related emergency room visits for Health and Human Services Region 10, which includes Alaska, Idaho, Oregon, and Washington, for all of May and June — the total was 3,504 visits but 79 percent (2,779) of these occurred during six days (June 25–30), when most of Oregon and Washington were under an excessive heat warning. The mean daily number, researchers found, was more than 69 times higher than for the same period in 2019.