I am thinking of starting a worm bin. What kinds of things should I consider. I live in the Desert of Southern California near Palm Springs. It gets around 103 during August and During December/January, it does get into the 20's sometimes. I was thinking of starting small, in like a 5 gallon bucket to just get started.

Because you have such a swing in your temps, you may first have to figure out where to put your worm bin before deciding what type to use. Worms prefer a pretty narrow temperature range for optimal functioning. Ideally, 60 to 80 degrees although you can fudge a few degrees either way before they slow down. Mine stay in my garage all year and my garage is heated in the winter to around 55 to 60 degrees.

My parent had worm beds here along time ago and they had them outside and from what I remember them mentioning and from I can remember seeing they didn't have to much problems, but then again they were in the ground and not a container.

You might do some browsing and see how to set up a 5-gal container in the ground. Below ground would definitely be cooler. I'm not familiar with that setup but I'm guessing you could drill a couple of holes in the bottom of your bucket for drainage and put some screening on the bottom to keep the worms in the bucket. You might need a cover for the bucket to keep critters out. Similar to a composter.

The ones my parents had (bed wise) was not in buckets or anything. When some of the houses were built back in the 1980's the builders were finding worms like crazy. The houses were 1000 feet away.

My father had a yard waste compost pile back under the trees (shady lot) and he would always go there for worms and nightcrawlers for fishing and he didn't import the worms.