Residents of the San Francisco Bay Area and Northern California woke up Wednesday to dark orange skies as a blanket of smoke from the state’s massive climate change-fueled wildfires smothered the region. The thick smoke blotted out so much sunlight that temperatures dropped well below forecasters’ predictions, with meteorologists comparing the effect to a nuclear winter. Many residents described the scene as “apocalyptic.”

The fires have also devastated Oregon, where dozens of blazes have destroyed hundreds of homes and even entire towns. Governor Kate Brown said it could be the greatest disaster in Oregon’s history.

Gov. Kate Brown: “I want to be upfront in saying that we expect to see a great deal of loss, both in structures and in human lives. This could be the greatest loss of human lives and property due to wildfire in our state’s history.”

The fires left at least seven people dead across Washington, Oregon and California. More fires are raging in Montana, Colorado and Utah. Meanwhile, new satellite data show fires in Brazil’s Amazon region leaped to a 10-year high in August, with many of the blazes consuming virgin forest rather than already-deforested areas.