Temperatures are skyrocketing yet again in the Pacific Northwest as the second major heat wave of the summer overtakes the region. This heat wave is not nearly as intense as the “unprecedented” event in late June, but is still bringing temperatures up to 15 to 25 degrees above normal.

The excessive heat comes as the region’s drought situation becomes more severe. Drought conditions blanket over 93 percent of the Pacific Northwest, a 38 percent leap from just three months ago, according to the U.S. Drought Monitor.

The combination of heat and drought have created tinderbox conditions away from the coast. The National Interagency Fire Center lists 37 active large blazes in Oregon, Washington and Idaho, including the Bootleg Fire, which has charred more than 413,000 acres in south central Oregon.

Seattle hit 91 degrees on Thursday, a dozen degrees warmer than average. Spokane managed to climb to 96 while Portland, Ore., spiked to 98 degrees. That’s just the start of a multiday stretch of extreme heat that could shoot highs up over 110 degrees well inland.

Excessive heat warnings are in effect through Saturday for most of interior Washington and central Oregon, where highs will climb into the triple digits. Yakima and Olympia are under a heat advisory, which also stretches through Oregon’s Willamette Valley, including Portland.

Temperature will peak Friday or Saturday in most locales before a gradual, subtle cool-down ensues next week. By Wednesday or Thursday, the heat may shift to the northern Plains, sparing the Pacific Northwest of the meteorological torch that’s been baking the region time and time again this summer.

The unseasonable conditions that have plagued the Pacific Northwest are hazardous to humans and wildlife alike, altering habitats and making the biome virtually uninhabitable for some. Temperatures in the Columbia River, which goes through Washington and Oregon and exits the coastline north of Portland, are running several degrees above the safe level for salmon — causing lesions and heat-related injuries that are endangering populations of the fish.

Gizmodo reported that similar issues are unfolding in California, where officials feared all young salmon in the Sacramento River were in jeopardy of dying. State officials shuttled 17 million hatchlings to the sea instead.

While the upcoming heat, which could keep highs in the 90s both Friday and Saturday in Seattle and help Portland hit the triple digits on Friday, is significant, it pales in comparison to an “unprecedented” heat wave that redefined the region’s susceptibility to extreme temperatures back in late June. Portland climbed to a mind-boggling 116 degrees during that event while Seattle surged to 108. That beat Portland’s previous high by 9 degrees.

Scientists estimated that heat wave, born out of a perfect recipe of overlapping meteorological features standing on the shoulders of long-term warming, was made 150 times more likely by human-induced climate change. In other words, a heat wave of that magnitude would not have happened without human influence.

The same episode broke the Canadian national record temperature three days in a row and helped Lytton, B.C., hit 121 degrees. The town burned down later that week.

The hot temperatures are sapping the ground of moisture, reinforcing the drought and allowing readings to skyrocket even more. One hundred percent of the Pacific Northwest is experiencing abnormally dry conditions, with more than a fifth of the region enveloped in an exceptional drought ― the most severe category outlined by the U.S. Drought Monitor.

Both Seattle and Portland have gone a month and a half without rainfall. That’s just ten days shy of Seattle’s longest such streak on record. Portland is more accustomed to long stretches without rainfall. During the summer of 1967, the city went 71 days without any measurable precipitation.

Listing the impacts of severe drought, the U.S. Drought Monitor warned: “Unprecedented wildfires occur.”

The wildfires, which dot the map across the West, are taking advantage of the dry conditions and expanding to mammoth size. In addition to the Bootleg Fire, others, like the Dixie Fire in northern California, are pushing a quarter million acres. That same conflagration produced a fire tornado in June.

By sapping the ground of moisture, anomalously hot temperatures make the fires more difficult to combat too. The dry lower atmosphere could even spark some dry thunderstorms across the West on Friday. Dry thunderstorms are lightning-producing storms that drop little to no rainfall since it evaporates in dry air, resulting in lightning strikes that can spark ignition without being extinguished by heavy rainfall.

Meanwhile, the fires continue to release massive plumes of smoke, turning day to night near the fires and degrading air quality a continent away. New York City saw their most unhealthy air quality index in more than seven years last week, a product of particulate matter from wildfires in western North America surfing the jet stream east. Air quality alerts are up for much of the Intermountain West and the Upper Midwest, including in cities such as Minneapolis and Des Moines.

“The smoke will cause unhealthy air quality at times and may cause health impacts,” warned the National Weather Service in Omaha. “This may be especially impactful for individuals with respiratory problems, elderly, and young children.”

Residents were advised to minimize time spent outdoors.

Looking ahead, prolonged hot and dry weather is expected into the autumn in the West, around the same time that offshore wind events increase in frequency and intensity. That will bolster wildfire risk even more, and it’s likely that devastating wildfires, extreme fire behavior and suffocating pollution will be pervasive in the months ahead.