Brood patches allow the transfer of heat to eggs for their successful embryonic development, and in many species determine egg temperature during incubation. We investigated brood patch development of Magellanic Penguins Spheniscus magellanicus in Isla Quiroga, Argentina, during 2012–2013. Here, we evaluate if brood patch development (in a narrow sense i.e. increase of the brood patch area and temperature measured with an electronic probe thermometer) varies according to laying date of the eggs, and with respect to adults' body condition and size, total clutch volume, and/or the sex of the adults. We found that brood patch temperature reaches its maximum when egg laying is finished, while brood patch area is fully developed starting from the end of the first quarter of the incubation period. The later the penguins started to breed the warmer the initial brood patches — when first egg is laid. Besides, the incubation period was shorter in penguins breeding late. Furthermore, adults in a good body condition had cooler initial brood patches than adults with poor body condition. In contrast, total clutch volume, body size index, and sex of the adults were not related to brood patch development. We conclude that initial brood patch temperature in Magellanic Penguins is associated with environmental factors, like laying date, and physiological attributes, like body condition.