I can find temps on line, but is it humid? I live in PA and we deal with high humidity in the summer. Looks like we can expect temps in the low 90s, but if it's humid that makes it a lot worse! What about in San Diego and Annaheim?
Thanks!

Temecula is not humid in comparison to PA. San Diego will be cooler than Temecula, Anaheim somewhere in between. Of the three choices you mention I would choose either San Diego or Temecula, Anaheim has nothing to offer besides the theme parks and strip malls.

It is not humid all the time in July, but there is a Southern California monsoon season (which we are experiencing right now). You may get several days or a week in a row. If you are near the coast it is cooler although it is still humid during the monsoons.

I live very close to Temecula. It can definitely be hot in July even hitting around 100. However, unless it's like the weather we've had the last few days, the heat is more of a desert heat. Temecula can get windy especially in the afternoons and it's a dry hot wind. The wineries in Temecula are very nice but if you can go during the week as they get crowded on the weekends.