The answer to 'why is my mosquito swarms' is that mosquito infestations are often caused by standing water near your home. Mosquitoes breed in stagnant water sources like birdbaths, gutters, old tires, or other containers. Symptoms include being swarmed by mosquitoes when outside, especially at dawn and dusk. To solve the problem, you'll need to identify and eliminate any standing water sources around your property.
If the mosquito problem persists or is severe, it's best to call a professional pest control technician. They can inspect your property, identify the root causes, and implement more comprehensive mosquito control measures that may include larvicide treatments, fogging, or other methods to reduce the mosquito population.