Cirrus clouds are ice clouds formed at very high levels in the sky. There are several types of Cirrus clouds. This discussion only applies to cirrostratus that looks like the picture.
These clouds are usually caused by a weather system passing to the north. They may also be caused by contrails providing moisture and soot to seed moisture already in the sky.
Cirrostratus clouds can be very thin. How thin will determine the forecast for the evening. In my own personal experience it is equally likely that the clouds will dissipate, that the clouds will stay and be thin enough to view through, or that they will be too thick.