That is one way of phrasing it, depending on your relation with your boss I would adjust it to suit the formality level. Expected could be interpreted as sllightly accusatory depending on how thick-skinned the boss is, some may see it as if you were indicating tardiness. But as with many things, this depends on the person and your relation. I would recommend against it unless you know eachother well,.
If you are informal with one another, write accordingly. I would in any case phrase it with why you need to know if and when the boss would be in the office.
I need to discuss A, B and C with you today. When is a good time?
This focuses on the tasks you need help with or your boss's input, not whether or not the boss will be in the office. If needed you could also add that a direct input onsite is necessary, but only if this is the case of course.