I was married in April. Texas is weird. We have "monsoon" like rainy seasons where once or twice a year--somewhere between March and early July and then October through November--we get a week or so of rain.
It POURED cats, dogs and small children the morning of the wedding. At the time the ceremony was supposed to start, just as people were finally coming into the church bedraggled and wet, the sun broke and the rest of the day was beautiful.
You just have to pick a date and pray for the best.
Though there's no way I'd have one between July and September. Texas mornings will start cooling off now, but days are sill likely to heat up into the 90's or 100's through the end of the month.
Heck, of course there are some years I wear shorts and T-shirts at Thanksgiving and Christmas and have to dig out the sweater and jacket for a freak snow/ice storm in March.
As they say, if you don't like the weather here, wait a minute... it'll change.
Good luck!