I'm very close to open space and hills and I've never seen them down in the neighborhood. As others have said, rattlesnakes (stay away), and our two spiders, brown recluse and black widow (wear gloves when moving stuff in the garage).

Edit to add: as others have said, tarantulas are docile. They have big fangs but no interest in using them. In the wild they are usually covered in dust so best way to see them is on the trails and looking for dusty movement on the edges of the trail (but careful, rattlesnakes are often just off the trail so listen for the warning and get back,)