Just because they are not swarming around you for a meal does not mean mosquitoes are gone, they just do not feed during the winter months. There are different strategies that mosquitoes use to survive, depending on the species.
Some species die off in the winter leaving behind the next generation on the ground as eggs, waiting for the return of gentle rains and warm weather. There are also some species that hibernate for the winter. It is actually not a true hibernation as you would think, but called “diapauses”, which is a state where they are able to temporarily shut down their development. They are known to hibernate close to the places that they live when it is warm. This means they are probably still around your yard hiding out; in leaf piles, hollow trees, old mole, squirrel and mouse holes as well as crawl spaces, cellars and basements. In preparation for the winter nap, the females will bulk up on sugar and nectars from rotting fruits. The males on the other hand die. They have done their job to ensure the next generation and it appears they are no longer needed!
Some mosquitoes will come out early and hatch if there is a warm spell, even if there are still areas of snow on the ground. These are referred to as “snow mosquitoes” as they are from several different species, usually the ones that live in the northern U.S. at high elevations. The adults die off but leave behind assurance that the next generation will continue the species.
In areas of the U.S. that have mild winter weather, mosquitoes may be seen occasionally all year long. But if you are wondering if they will be back in full force, you are right. Come spring when the earth is being re-born, they will re-appear and become a common pest that we must routinely deal with again! Be prepared to protect your family from these pests! Besides being annoying, they can be the carriers of diseases!