It is like this pretty much every summer. 21 days is a pretty long stretch, but July, August, & September are usually brutal here. I have been in Tejas for 10 years now and it seems like we had a stretch of 35 to 40 days one year where we broke 100 every day. Most summers we will have a stretch of at least 15 days and it isn't uncommon to have two or three stretches of 15 days or so. My first summer in Tejas (Waco), it was 114 on Labor Day. Thought I could handle it because I had come from the humidity of MS and this was a dry heat. Played 18 holes of golf that day. Got home about 6:30 in the evening, laid down on the bed to rest, and my wife woke me up the next morning when I had to get up for work.
Summers are brutal here. Know that this year isn't an anamoly, it is pretty much the norm.