The answer to 'why is my fire ant swarms' is that fire ants have built a large nest or colony in your yard. Fire ants are aggressive insects that form large mounds and can quickly overrun an area. Common signs of a fire ant infestation include seeing lots of ants swarming around a mound, feeling painful stings if you disturb the nest, and observing piles of dead ants around the mound.
Fire ant swarms can be caused by a few factors, including warm, moist weather that allows the colony to grow rapidly, disturbances to the nest that force the ants to relocate, and lack of effective pest control measures. While fire ants can be managed with DIY methods, it's often best to call a professional pest control technician, as they have the expertise and products to safely and effectively eliminate a fire ant infestation.