About 30 million people are under excessive heat warnings or advisories as a heat wave sweeps the Western U.S., bringing potentially record-high temperatures on Sunday, according to the National Weather Service.

Why it matters: The heat wave comes after some regions in the Pacific Northwest saw temperature records shattered last month, with the same "heat dome" effect that is engulfing the West now, the New York Times reports. Human-caused climate change has exacerbated the frequency of these extreme heat events.

State of play: California's Death Valley saw 130°F temperatures on Friday, and could reach such highs again on Sunday. Those temperatures could set a record, if verified, since scientists have disputed a 134°F reading from 1913.

• Palm Springs, Calif. saw a record high of 120°F Sunday, beating the previous record of 118°F it reached Saturday, Los Angeles Times reports.
• The heat has caused wildfires and led to evacuation orders in several states, including California, Oregon, Idaho, and British Columbia.
• The Bootleg fire in Oregon was threatening transmission lines that supply California with power, after doubling in size to 120 square miles on Saturday.
• A huge wildfire burning in California's Plumas National Forrest, part of the duo of fires dubbed the Beckwourth Complex fires, doubled in size between Friday and Saturday, and even generated its own lightening, according to the L.A. Times. As of Saturday was only 8% contained.
• Las Vegas tied its all-time record high of 117°F on Saturday afternoon, AP reports.

What to watch, via Axios' Andrew Freedman: Utah tied their state heat record yesterday, and Vegas could break theirs today after tying it on Saturday. More importantly, the fires burning in California and Oregon and Washington will flare up again.

Go deeper:Northwest "heat dome" signals global warming's march