Stumbled across this textbook from 1980 today. It’s remarkable how accurate the first sentence remains today.

Lastly, our analysis is specific to the LA fires. For a comprehensive assessment of the diversity of ways in which climate change and other factors have impacted wildfire in California to date, see Williams et al. (2019) and MacDonald et al. (2023).

Given the extreme aridity and fuel abundance, the Santa Ana winds that arrived on Jan 7 were the final ingredient in a perfect recipe for major wildfire development. We find that this was indeed an exceptional Santa Ana event, though perhaps not entirely unprecedented.

Another major factor in the aridity of fuels leading up to the fires was the abnormal lack of precipitation. The total precipitation in LA from May 1, 2024 through January 8, 2025 was extraordinarily low, only 0.29”, the 2nd driest period going back to 1877.

A likely factor underlying the extreme fuel aridity prior to the fires was the anomalously hot summer-fall period of 2024. We show that the summer-fall of 2024, with a mean temperature of 67.1°F, ranks as the 3rd hottest since at least 1895 in coastal Southern California.

Moisture levels in fuels were well above normal following these wet winters. However, they then exhibited a precipitous decline over summer and as the wet season failed to materialize. By Jan 7, dead-fuel moisture was 6th lowest on record for that date.

We first note that the 22-23 and 23-24 water years were very wet across the LA region, which led to a buildup of vegetation in wildlands. Thus, the hillsides and mountains of LA entered the 2024 fall fire season with substantially more grass and chaparral fuels than is common.

#PalisadesFire full timelapse (~10:35am-4:10pm) view from Santa Monica thus far, courtesy of
@alertcalifornia.bsky.social
(cameras.alertcalifornia.org?pos=34.0754_...) #CaWx #CaFire