Hikers unfamiliar with the range should know that only a few of its hikes are "easy". The terrain, especially in the south is very steep and trails are not always kept clear. If you leave the trail and start scaling the rocks you will find out quickly that 1.5-billion-year-old mudstone is very brittle and not a very reliable handhold. Climb around with caution. In the daytime it can be very hot, but nights are very cold, so pack accordingly. Though the Missions aren't huge, it is always a good idea to bring a map. The USGS topographic maps of the area are available at local sporting goods stores and not a bad thing to have in your pack.