Can you eat watermelon that has been left overnight?

Generally speaking, whether overnight watermelon is edible mainly depends on the method and environmental conditions used for preservation. The specific analysis is as follows:

If the watermelon is promptly sealed with clean plastic wrap after cutting, quickly placed into the refrigerator for cold storage, and stored for no more than 12 hours, it is generally safe to eat after removing the outer 1–2 cm of flesh thoroughly. A low-temperature environment inhibits bacterial growth, while sealing prevents odor transfer and cross-contamination. Following these strict handling procedures can reduce the risk of consumption.

If the watermelon is left at room temperature for an extended period after cutting, stored in the refrigerator without sealing, or refrigerated for over 24 hours, it is not recommended for consumption. Bacteria multiply rapidly at room temperature, easily leading to the growth of numerous pathogenic bacteria; lack of sealing allows bacteria to adhere to the surface of the flesh, which cannot be completely eliminated even by refrigeration. Consumption may lead to gastrointestinal discomfort such as diarrhea and abdominal pain.

When storing watermelon, after cutting, it should be sealed and refrigerated promptly to avoid repeated removal and exposure to room temperature. Before consumption, check if the flesh has an unusual odor or abnormal texture. If unsure about its safety, do not consume it. Each time you eat, use clean knives and utensils, and avoid contact between saliva and the remaining flesh to prevent bacterial growth.