Pretty much the same thing Texas as here in Kansas, heat is a killer.
In Early September I put cabbage and Brussel sprounts in low tunnels to protect them from cabbage loopers and diggy squirrels. That worked until we got a 99 degree day about 2 weeks ago and I did not get them out of the low tunnel in time.
I removed the covers and put them under Mosquito netting that would allow the Sprouts to get tall, but the damage was done to 3 of the Brussel sprouts. I think 4 out of 8 will survive, but none of them will get full size.
The cabbage is doing pretty well so I pulled off the netting today. (Have only seen 1 looper moth in the last week and let them get some sun.) I will cover them up tomorrow night since we will get a freeze Monday and Tuesday. (And will pick the remaining green tomatoes and a bunch of basil.)