The answer to 'why is my wasp swarms' is that you likely have a wasp nest or hive near your home. Wasps build nests in sheltered areas like under eaves, in trees, or in wall voids. When the nest grows large, you may see a swarm of wasps flying around it. This is normal wasp behavior as they defend their nest and search for food.
However, a large wasp swarm can be a serious threat, especially if the nest is located close to your home's entrance or areas where people frequently gather. Wasps are aggressive and can sting repeatedly, which can be dangerous for those with allergies. If you have a large, active wasp nest near your home, it's best to call a professional pest control technician to safely remove it.