Heat stress significantly impacts dairy cattle production in the humid subtropical southeastern United States. As ambient temperatures rise, evaporative cooling mechanisms like sweating and panting become less effective, especially under high humidity. This leads to increased body temperature, reduced dry matter intake (DMI), and lower milk yield. Environmental modifications such as shade, improved ventilation, and cooling systems (e.g., fans, sprinklers, and tunnel ventilation) help reduce body heat and improve DMI. Genetic selection for heat tolerance is possible, but continued selection for high productivity without considering heat tolerance may increase susceptibility to heat stress. Nutritional needs change during heat stress, requiring rations that account for reduced DMI, increased nutrient density, and maintenance of rumen function. Future dairy production in hot, humid climates will require improved cooling, better nutritional formulations, and genetic advancements focused on heat tolerance. Heat stress also affects reproductive performance, with heat-stressed cows producing smaller calves and lower-quality colostrum. Genetic variation exists in heat tolerance, with Brahman cattle showing greater efficiency in heat loss. Nutritional management must include increased water availability, adjusted diets to meet higher nutrient demands, and strategies to maintain milk yield and reproductive efficiency. Overall, managing heat stress in dairy cattle requires a combination of environmental, nutritional, and genetic strategies to maintain productivity and health.Heat stress significantly impacts dairy cattle production in the humid subtropical southeastern United States. As ambient temperatures rise, evaporative cooling mechanisms like sweating and panting become less effective, especially under high humidity. This leads to increased body temperature, reduced dry matter intake (DMI), and lower milk yield. Environmental modifications such as shade, improved ventilation, and cooling systems (e.g., fans, sprinklers, and tunnel ventilation) help reduce body heat and improve DMI. Genetic selection for heat tolerance is possible, but continued selection for high productivity without considering heat tolerance may increase susceptibility to heat stress. Nutritional needs change during heat stress, requiring rations that account for reduced DMI, increased nutrient density, and maintenance of rumen function. Future dairy production in hot, humid climates will require improved cooling, better nutritional formulations, and genetic advancements focused on heat tolerance. Heat stress also affects reproductive performance, with heat-stressed cows producing smaller calves and lower-quality colostrum. Genetic variation exists in heat tolerance, with Brahman cattle showing greater efficiency in heat loss. Nutritional management must include increased water availability, adjusted diets to meet higher nutrient demands, and strategies to maintain milk yield and reproductive efficiency. Overall, managing heat stress in dairy cattle requires a combination of environmental, nutritional, and genetic strategies to maintain productivity and health.