Background and aims <p>Canopy–air temperature difference (<i>Tc-Ta</i>) information derived from the canopy temperature (<i>Tc</i>) has been shown to be an effective cue for crop soil water stress in past studies attributed to its strong linkage with physiological processes. Nevertheless, a gap exists in how much water should be irrigated rather than just the tendency to cue the need to irrigate in potential irrigation campaign. This study therefore aims to quantify the potential irrigation volume using the <i>Tc-Ta</i> field collection and developed a conceptual model.</p> Methods <p>A conceptual model was developed, which is soil water content (SWC) with <i>Tc-Ta</i> similar to the triangle in different daytime periods. Potential irrigation volumes were evaluated basing on the SWC quantified by the conceptual model, in which irrigation scenarios were hypothesised from low to high soil moisture.</p> Results <p>The predicted soil moisture yielded a more pronounced overestimation from the model-based Wet edge function for maize than for wheat at various <i>Tc-Ta</i> thresholds (0, 1, 2), it should be emphasised that both methods showed convincing results (R² ranging from 0.5 to 0.7). Since the daily time response was more pronounced in wheat than in maize, especially for high soil moisture treatments. The errors between the measured and predicted irrigation volume (calculated from the <i>Tc-Ta</i> conceptual model) were less than 25 mm in both hypothetical irrigation scenarios (from low to high SWC) for wheat and maize at varying times of the day. Multiple types of empirical water stress indices (<i>CWSIs</i>) showed weaker potential for indicating the amount of irrigation because of the weak linear relationship between <i>ΔCWSIs</i> and the actual irrigation amounts in the two hypothetical irrigation scenarios. Additionally, Correlation evaluation showed that crop intrinsic factors water status and leaf area index were more correlated with <i>Tc-Ta</i> for both wheat and maize.</p> Conclusions <p>Our results suggest that the worth of <i>Tc-Ta</i> in signaling potential irrigation volume from the developed conceptual model.</p>