The report updates the picture for California’s hotter future with a projected 4-degree Fahrenheit increase in average temperatures and 50% longer heat waves by the middle of the century. Even more warming is expected farther inland where temperatures are already highest.

In the Los Angeles region, which makes up 43% of the state’s population and comprises Los Angeles and Orange counties and parts of the Inland Empire and Ventura, inland areas are expected to see the hottest day of the year exceed 115 degrees by mid-century. San Bernardino, which already saw August temperatures peak at about 109 degrees this year, is expected to see 120 days a year above 95 degrees, compared with 81 days historically.

Climate change is not expected to change average precipitation overall, but it will become even more skewed and sporadic, so wet and dry years both will become more frequent in California, and droughts will last longer. The increased heat means the state will lose about 40% of its snowpack by mid-century, an important water source from the Sierra Nevada on which Southern California relies. The city of L.A., which brings in water from elsewhere for the vast majority of its supply, will be getting 7 to 13% less in imports by mid-century because its other sources, too, are drying up.

The total area that burns in fires each year will increase dramatically — 50% by mid-century — without changes in land management. The effect will be strongest in the mountains. Native chaparral, the shrubby natural landscapes of the foothills, are becoming stressed and being replaced by grasses and other fire-prone invasive plants. Changes in rain and snowfall could lead to more seasons like the ones before the 2025 Eaton and Palisades fires, during which unusually wet winters fueled lots of green plant growth that then became tinder dry over eight months without rain.