Gnats
I'm not sure I know the difference between the two but I get those in my house every year around this time. Make sure you take your trash out regularly. I notice them flying around my trash can if it's starting to get full.
During the daytime I'll turn off all the lights in the house and raise the blinds on a few windows and wait a couple minutes for them to flock to the window one by one chasing the sunlight. Then I'll smack em with a rolled up magazine or something. It's actually kinda fun but I'd rather not have to deal with them.