I know for me, my depression is predictable while my anxiety is both predictable but unexpected depending on situations.
I know I get depressed talking with my Mother and Sisters.
I know sad news or a subject close to my heart can cause depression. Certain times of the month cause depression.
If someone else in my family is depressed sometime I do to.

For anxiety; My parents, my sisters, church, meetings with my boss cause me anxiety. But so does unexpected surprises... of any kind!
Reason why I try and have a backup plan.