We are near a tidal lake/estuary in Plymouth. We haven't noticed any more flies, perhaps 1 or 2 in the house but not much more. We also get a few mozzies or things that look like tiny daddy long legs/crane flies but again not a significant increase.
I did see 2 horse flies in here last week which were the first I've ever seen here. But since then, they seem to have gone.
I wonder if you are near any cattle or large mammals where you live? When we lived on a farm, we'd often fill up 3 sticky fly papers to busting within a week