ABSTRACT Climate change significantly impacts the food industry, particularly affecting seafood quality and freshness due to temperature changes. This study aimed to track mackerel quality indicators at auction sites and assess the impact of weather changes on its quality and freshness. During the summer, acid value (AV) varied from 0.70 ± 0.19 to 3.61 ± 0.52 mg/kg, while the peroxide value (POV) in the 300‐g mackerel group ranged from 4.8 to 7.09 meq/kg. This group also exhibited volatile base nitrogen (VBN) values exceeding 25 mg/100 g as the auction progressed. Total bacterial counts (TBC) increased beyond 4 log 10 CFU/g, indicating that microbiological contamination would reach the initial spoilage level by the end of the auction. Temperature and season significantly ( p < 0.05) affected mackerel quality, with strong correlations ( r > 0.7) between temperature and fat oxidation indicators such as POV. The findings reveal that mackerel samples from summer auctions experienced significant hygiene and quality changes. Notably, 200‐g and 300‐g mackerel samples showed different patterns of change. This study underscores the unique importance of season and sample weight in assessing seafood quality under climate change, providing a foundation for better distribution and supply of high‐quality fresh mackerel amidst rapid climate changes.