Many sexually selected traits are static throughout the breeding season. Some vary within the breeding season, however, typically in response to physiological changes. Most work attempting to understand the mechanisms underlying phenotypic changes has occurred in the laboratory, with comparatively less research examining how changes to physiology affect signal production in natural populations. Here, we report intraseasonal plasticity in abdominal and throat patch color of Prairie Lizards (Sceloporus consobrinus), and examine how changes in body size, body condition, and testosterone underlie intraseasonal variation. We found that changes in testosterone best explain why throat patches of Prairie Lizards become less blue throughout the breeding season. If females reproduce with males based on patch color, then individual changes in patch phenotypes could have important consequences if signaling morphology is asynchronous among males.