This study aimed to investigate the early-age compressive strength development of structural concrete cast during the summer season, along with that of mold specimens used for strength monitoring of structural concrete. Concrete mixtures were designed in both ordinary strength (OPC) and high strength (HPC) categories. Structural members, including columns and walls, were fabricated, while mold specimens measuring 100 × 200 mm were prepared and subjected to three different curing regimes: underwater curing, field air-dry curing, and standard curing. To assess the early-age compressive strength of the columns and walls, core samples were collected after 1, 3, 7, and 28 days of curing, and corresponding core specimens were tested for compressive strength. Concurrently, the compressive strength of mold specimens was also evaluated at the same ages. During the curing process, the internal heat of hydration of the structural concrete was monitored, enabling comparison of the equivalent age and cumulative temperature with those of the mold specimens. The findings revealed that the structural concrete columns exhibited the highest compressive strength consistently from day 1 to day 28. In contrast, mold specimens initially showed the lowest compressive strength under standard curing, whereas by day 28, those subjected to field air-dry curing recorded the lowest compressive strength.