We have been to the Sinai 3 times now. Once to Sharm, once to Taba and once to Dahab. It's an amazing place. We normally go in July/August, when you can pretty much rely on 40°C+, we have seen 50°C+ too!
This time of year, I imagine that 30-35° would be likely and consistent too. In 3 separate trips, we haven't seen so much as a drop of rain. I would imagine October to be similar temps to that.
It's quite a primative place. The Airport is basic and lots of teenage troops walking around with guns. Take care if you have a good-looking Girlfriend, particularly if she is Blonde! They do like that! Harmless though. I think I got offered 3 camels for Beccy on one occassion, but plenty of nudges and winks!
We stayed in the Hyatt Regency in Sharm, it is a 5-Star Deluxe hotel and really lives up to that. I think it is still arguably the best hotel in Sharm.

It has its own private Coral reef and miles-and-miles of Marble floors etc. You just couldn't hope for better. They have their own Shuttle bus into Sharm town, where you can find a mall (if they have rebuilt it, that was the one that was bombed) and some familiar places, like KFC, Hard Rock etc. We hardly ventured out of the hotel though. The Hotel staff are among the friendliest people I have ever met and consist of 99% male, you hardly ever see a woman working there. It is funny watching the fully cloaked-up Arab women in the swimming pool though!!
Hope this helps!!