The human body adjusts to a remarkable degree. The first days or maybe weeks of a new bike commute can be a sweaty experience but it ceases to be a problem quite quickly. If you were in the gym, that would be your cue to increase workout intensity, but since it's a bike commute, there's no need.

For a grade over a certain percentage and longer than some duration, it is probably indeed the case that sweating is unavoidable. But you can usually trade a short steep grade for a longer shallower grade, even in San Francisco. The absolute worst portions of SF hills are usually only a block or two long and are much more likely to be found where you live, not where you work.