Yes, there are two major factors that affect the ability to heat a pool.
One is how much heat you’re able to put in the pool. When the ambient air temperature gets colder there is less free heat available for the heater to transfer into the pool water. When it’s colder, allow your heat pump to run as long as it needs to achieve the temperature you desire. You may need to adjust the filter pump clock to run longer so the heat pump does not shut itself off as a result of no water flow.
The second is how much heat you’re able to retain in your pool. The greatest cause of heat loss from a pool is ambient air temperatures colder than your pool water removing the heat from the pool. You may want to invest in a solar cover. A solar pool cover will insulate the surface of your pool greatly reducing the amount of heat loss. This will also save you money.