I own a 4 oz. windbreaker from Montbell that is one of my favorite pieces of gear/clothes. It was a replacement for a worn out 3.5 oz. Montbell windbreaker I wore to death. They altered the design between my first one and this one, adding pockets and a half ounce. Both have hoods. I gave my wife one and she was immediately hooked, too.
For such a tiny weight it provides far more warmth than you'd expect, but its breathability makes it better choice than a raincoat to wear while actively hiking. It's bugproof, which is another excellent feature, since I hate deet.
It is the first layer to go on as the sun gets low and the nighttime chill begins to creep into the mountain air. In cold rain I've layered it under my rain jacket for added warmth and a bit more protection from seepage. Last, it packs small enough to shove in my pocket when I'm exploring the environs away from my campsite.
I even use it sometimes when it's windy.
Maybe it wouldn't be quite so useful in Texas as here in Oregon, though.