Fig. 3: Fire danger trends across California from 1990 to 2022.

a Integrated Human-centric Wildfire Risk Index (IHWRI); b critical fire-weather days; c wildland-urban interface (WUI) area; and d housing units within WUI. The delta symbol (Δ) denotes the average annual percentage change for each trend line over the period from 1990 to 2022 and black lines indicate linear trend lines. The IHWRI values in sub-plot (a) are divided by 1010 for better readability.