Watermelons can ripen to some extent in the fridge, but they won't continue to ripen in the same way as they would at room temperature. Ripening is a process that involves the conversion of starches to sugars, leading to improved flavor and texture in many fruits. However, this process is temperature-dependent.
When a watermelon is harvested and mature but not fully ripe, placing it in the fridge may slow down the ripening process and help preserve its current state for a short time. However, if the watermelon is unripe when placed in the fridge, it is unlikely to reach its optimal ripeness level.
On the other hand, if the watermelon is already fully ripe when placed in the fridge, it will remain ripe for a few days. The cold temperature of the fridge can help maintain its current level of ripeness and slow down the spoilage process.
Ideally, it's best to allow watermelons to ripen at room temperature before refrigerating them, as this will ensure the best flavor and texture. If you have a fully ripe watermelon, you can store it in the fridge for a few days to keep it fresh, but for the best taste experience, consider consuming it soon after ripening.