"Pasadena/Clear Lake" is a fairly large area; could you be a bit more precise as to your location?
Since you say the wind is southerly, (the prevailing direction in that area) I agree with others that what you are smelling is probably emanating from Texas City. (I also worked on/in most of the plants in TC. )
My guess is that you are smelling one of the PVC (PolyVinylChloride) precursors (?Polyvinyl Acetate?) from the Union Carbide Texas City plant. The nectarine-like smell was so pervasive in the plant that I stopped eating nectarines for several months after working there.
However, I never recall smelling the UC plant as far inland as where we lived. (I went to grade school in Golden Acres -- in the Pasadena School system.) If you are north of Clear Lake, there must have been a significant release for you to smell the UC plant...
Glad it has tapered offf -- and hope your "smeller" hasn't just gotten fatigued and gone inoperative.
If you find anything out, how about a ping -- or a FReepmail...
Good luck...
As I said in a previous post:
"Southeast side of town, just south of Pasadena and next to Ellington field."
Yep, the smeller is working fine this morning!