Despite the absence of direct sunlight, heatstroke remains a significant risk during Taiwan’s summer, with doctors warning that “pre-rain damp heat” can be even more dangerous. This phenomenon occurs when humidity levels are high before rainfall, hindering sweat evaporation and the body’s natural cooling process. Individuals may experience heatstroke even when not directly exposed to the sun, as the body struggles to regulate temperature in the humid air. Five key warning signs include persistent sweating, headache, dizziness, nausea, and muscle cramps; immediate medical attention is crucial upon experiencing these symptoms. Doctors advise staying hydrated, seeking shade, and avoiding strenuous activity during these conditions. Vulnerable populations, such as the elderly and young children, are particularly susceptible and require extra precautions. High humidity combined with heat creates a dangerous environment, urging heightened awareness and proactive measures to prevent heatstroke.