There are a lot of moderate climbs in First Creek Canyon at Red Rocks. There are also some very easy bolted sport routes at second pullout - Magic Bus and Black Corridor areas. If you climb in the shade, you can climb all summer. You just have to go out early or late. Midday is bad. Also, realize that you will be approaching First Creek through the desert, probably for 45 minutes. It will also take that long to get back to your car - allow plenty of time before dark! It is very easy to get lost when everything looks the same. The approach and hike back to your car are what kills you, if you are climbing in the shade, it can be quite pleasant.
Finally, if you are going to walk in and out in the full sun, leave a note on your car so we can scavenge the gear off of your dessicated body.