Abstract The climate of the Mediterranean‐like Western US (MWUS), roughly encompassing Oregon, Washington, and California, is characterized by warm‐to‐hot dry summers and cool, wet winters. The transition between these seasons is driven by an increase in atmospheric baroclinicity. During this transition, the likelihood of both strong wind events and significant precipitation increases. This transition typically coincides with a minimum in regional fuel moisture, a time of high risk for severe fire weather. Therefore, when strong winds occur before significant precipitation, large wildfires can occur. While it is well understood that warming is increasing evaporative demand and lowering fuel moisture across the region, less is known about changes to the timing of precipitation and wind. Toward addressing this gap, we use 11 regional climate models to assess projected changes to the timing of the first significant precipitation and the first strong wind events across the MWUS. Historical model simulations reproduce the broad spatial and seasonal patterns of rain and wind onset. The models project that by the end of the century under an aggressive but plausible warming scenario, the average date of the first strong wind will occur later in the year across most of California and some of the Pacific Northwest. A majority of models also project a later rain onset over the Pacific Northwest, but this shift is generally smaller than wind, and models disagree on significance. Models project a slight decrease in the likelihood that wind onset precedes rain onset but disagree on significance and sign of change.
Taylor et al. (Sat,) studied this question.