I wouldn't wear seersucker in the middle of winter, just because I'm somewhere where the daytime high will be in the mid-70s.
I won't go so far as to require it to be between Memorial Day and Labor Day, no. Come springtime, if it's going to be in the 80s, go ahead and put on the seersucker. I've got no problem with that. Breaking the seersucker rule under those conditions shows that you're confident enough to know when it's okay to break a rule and show some original thought. Breaking the seersucker rule today just shows that one doesn't get it.
The blue blazer sounds like a perfectly acceptable choice, seeing as how it's essentially "weather neutral," and can be worn as appropriately pretty much year 'round. You want to wear a repp tie with it, fine. Not the only choice, but there's nothing wrong with it.
Tweed sounds a little off, given where you are and what the weather's like. Although if I had to choose between a relatively lightweight tweed and a seersucker suit, on a temperate January day, I'd absolutely go with the tweed. I mean, in a heartbeat.
As something of an aside, is seersucker all that common in SE Texas, even in summer? I've been led to believe otherwise. Not that there's anything wrong about wearing something which is locally a little uncommon, in the right circumstances.
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Michael