Low-lying morning clouds in Southern California coastal areas form the predictable "June Gloom" in early summer - at least, they used to. The combination of urbanization and a warming climate are driving up summer temperatures, reducing cloud cover and increasing the risk of bigger and more intense wildfires, reported Julie Cohen of UC Santa Barbara's The Current.
The scientists compared hourly cloud observations recorded by Southern California airports since the 1970s with a large database of vegetation moisture levels in the hills outside of Los Angeles. They found that periods of less cloud cover during the summer correlated with lower vegetation moisture and increased fire danger.
“Because fires can already be very difficult to control in these areas, a reduction in cloud cover and its effects on fuel moisture is likely to increase fire activity overall,” Moritz said. “In areas where clouds have decreased, fires could get larger and harder to contain.”
Conditions vary year to year, but Moritz said he expects fire danger to increase in California as climate change accelerates.