Abstract Airborne measurements over the Southeast US during the summer of 2013 revealed the evolution of nitrogen oxides and nitric acid that was markedly different from that over the Northeast US during the winter of 2015. We can reconcile the observed trends by invoking nitrogen oxide reservoir species formed under elevated NOx environments that then convert to HNO3. This process may represent a daytime loss pathway of NOx that is faster by many factors than the oxidation of nitrogen dioxide by hydroxyl radicals. We present measurements of a suite of organic nitrates made using online iodide‐ionization time‐of‐flight mass spectrometry and simple box modeling that support their role in controlling the net conversion of NOx to HNO3. Rapid loss of organic nitrates derived from biogenic volatile organic compounds, such as what we infer from this analysis, has significant implications for our understanding of oxidant budgets and top‐down NOx emissions assessments.