You might be surprised to find out that the weather is an important factor when it comes to installing your pool liner. That’s because the heat and humidity allow the liner to stretch properly. The ideal temperature to install your pool liner is between 60 and 90 degrees Fahrenheit, and anything above 90 degrees might be trouble because you don’t want the liner to over-expand. You’ll also want to make sure that if the temperature is within the desired range that it’s also sunny outside. You don’t want to install the liner when it’s raining because it can disrupt the whole installation process.