This is really strange and has occurred several times when driving in windy conditions:

Between the speed of 70 and 90 mph (120-145 kmh), I hear a noise thats coming from the front that is like a quick, repetitive thump/flap.

I heard it several times when driving with moderate wind gushing at some angles (can't tell which angle). I thought I was being paranoid. My wife commented previously about the noise, and so has my cousin this afternoon. He thinks its coming from underneath the car (front end).

I checked the plastic flap that is underneath the front bumper and its fully and securely fastened, so I doubt that its causing the (thump..thump..thump..thump) sound.

Could it be the front license plate?

Does it have to do anything with the fact that the front of the car sometimes squeeks when going over large speed bumps?

I'm really frustrated as this noise is intermittent and does not occur when driving in the city (where there is little wind). Noise only comes with certain wind angles during highway driving. Noise goes away above 90 mph. I'm worried