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<p>Wind reversals resulting in southerly flow along the California coast are not well understood in terms of how aerosol and cloud characteristics change. This gap is addressed using airborne field measurements enhanced with data from spaceborne remote sensing (Moderate Resolution Imaging Spectroradiometer), surface stations (Interagency Monitoring of Protected Visual Environments), and models (Navy Aerosol Analysis and Prediction System and Coupled Ocean–Atmosphere Mesoscale Prediction System), with a focus on submicron and supermicron aerosol, as well as cloud microphysical variables: cloud droplet number concentration (<span class="inline-formula"><i>N</i>_d</span>), cloud optical thickness (COT), and cloud droplet effective radius (<span class="inline-formula"><i>r</i>_e</span>). Southerly flow coincided with higher values of submicron aerosol concentration (<span class="inline-formula"><i>N</i>_a</span>) and mass concentrations of species representative of fine-aerosol pollution (NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="0723f17b5be9fc41c36a5585631feb47"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00001.svg" width="9pt" height="16pt" src="acp-24-9059-2024-ie00001.png"/></svg:svg></span></span> and nss-SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="277c1427ed297c2e5c45f7f988764cfe"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00002.svg" width="13pt" height="17pt" src="acp-24-9059-2024-ie00002.png"/></svg:svg></span></span>) as well as shipping and continental emissions (V, oxalate, NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="3fe22ea21bb8c3940d1d54b092ea883d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00003.svg" width="8pt" height="15pt" src="acp-24-9059-2024-ie00003.png"/></svg:svg></span></span>, Ni, OC, and EC). Supermicron <span class="inline-formula"><i>N</i>_a</span> did not change; however, heightened levels of acidic species in southerly flow coincided with reduced Cl<span class="inline-formula">⁻</span> : Na<span class="inline-formula">⁺</span>, suggestive of Cl<span class="inline-formula">⁻</span> depletion in salt particles. Clouds responded correspondingly in southerly flow, with more acidic cloud water and higher levels of similar species as in the aerosol phase (e.g., NO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="fa1148a5a7ab62133104fb46bf612014"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00004.svg" width="9pt" height="16pt" src="acp-24-9059-2024-ie00004.png"/></svg:svg></span></span>, nss-SO<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="5051a948f61d36bc48409cbb9c9d62b3"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00005.svg" width="13pt" height="17pt" src="acp-24-9059-2024-ie00005.png"/></svg:svg></span></span>, NH<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mo>+</mo></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="8pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="f1ca5762abf079d28af10bf21d382d4c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-24-9059-2024-ie00006.svg" width="8pt" height="15pt" src="acp-24-9059-2024-ie00006.png"/></svg:svg></span></span>, V), along with elevated values of <span class="inline-formula"><i>N</i>_d</span> and COT and reduced <span class="inline-formula"><i>r</i>_e</span> during campaigns with similar cloud liquid water paths. Case study flights help to visualize offshore pollution gradients and highlight the sensitivity of the results to the presence of widespread smoke coverage including how associated plumes have enhanced supermicron <span class="inline-formula"><i>N</i>_a</span>. These results have implications for aerosol–cloud interactions during wind reversals and have relevance for weather, public welfare, and aviation.</p>