It is possible to close your pool too early for winter, so experts agree that as long as the water is still warm, it’s okay to remain open — even if it is late into fall. Closing a pool too early will decrease the winter protection chemicals’ potency, possibly causing a rough opening in spring. Warm water can also cause algae to bloom, an issue you don’t want to have to deal with in the spring, especially if it’s been growing all winter long! So if you’re having a bit of an Indian Summer, extend the pool season a little bit. It may save you some time and money in the long run.