West LA Times

Record-breaking heat waves are affecting both coasts, but for some experiencing less intense heat, there may be a misalignment between perception and reality. In the Southwest, multiple inland areas broke all-time records, while densely populated coastal cities were simply hot, said UCLA climate scientist Daniel Swain in a live briefing delivered Wednesday evening. While much of the East Coast also sweltered, the central U.S. was slightly cooler than average – “and this has been a recurring theme in recent decades,” Swain noted.

Excerpts and timecodes from Swain’s discussion of extreme heat and wildfires are below, along with more discussion about another series of heat waves coming to the Southwest, how a reprieve in the heat could worsen wildfires, and why an increase in Weather Service heat and fire warnings isn’t just because of climate change.

Is it even hot if you can't feel the heat: “Something like 90% to 95% of the land area of California probably saw its hottest mid-June to mid-July period on record – and perhaps more than half of the state's population living in these densely populated coastal zones did not. So, really interesting questions here about the perception of reality versus reality itself.”

Heat records broken in California: “I assure you, it really has been damn hot inland, and record hot … A lot of parts of the Central Valley broke all-time records for the most number of 100- or 105- or 110-degree days, as the case may be in particular locations, in a single month or in a consecutive period. Some places actually saw their singularly hottest day on record. That's a pretty unambiguous statistic.”

Dangerous overnight highs mid-June to mid-July: “Virtually all of California, and now virtually all of Arizona and New Mexico, and now also parts of Colorado, Utah, Nevada and Oregon all saw record warm overnight temperatures for this 30-day period. So it's certainly true that it's been hot during the daytime but it's been even more anomalously warm at night.”

East Coast record heat: “Much of the eastern seaboard of the U.S. also experienced its warmest 30-day mid-June to mid-July period on record just now. The one part of the country that did not – and this has been a recurring theme in recent decades – is the central U.S.”

The Central U.S. outlier: “The U.S. Great Plains is one of the only places that saw even slightly cooler-than-average temperatures this summer so far, and they have been surrounded by regions that have seen all-time record warmth on all sides so definitely an outlier there… It is striking that this region continues to see less summer warming than most other places. Lots of research on that; some may have to do with major irrigation across vast scales.”

For a change natural ignitions driving California wildfires: “There are several very active wildfires in California right now. Most are relatively far from large population centers but they're burning in fairly remote densely vegetated heavily forested areas likely persisting for quite some time… Unlike some wildfire outbreaks now most fires currently burning were started by natural causes lightning rather than accidental human sparks common for wildfires sparked in California.”

Swain is a climate scientist with UCLA’s Institute of Environment & Sustainability. View his full conversation online or contact media relations for future Q&As or insights from him or other UCLA experts.

Alison Hewitt

Senior Media Relations Officer

UCLA Strategic Communications | Office Media Relations

ahewitt@stratcomm.ucla.edu | @ashewitt | @ahewitt.bsky

310-206-5461