The only thing I can think of, which might have an impact on the weather, is to have clouds of nanobots floating in the high atmosphere which can selectively become reflective or not.
When they are transparent, they let light through, and the energy reaches the ground as it would normally do.
When they become reflective, they bounce back light to space, removing it from the energetic balance of the underlying surface.
In the short term this would locally cool down the area upon which the cloud is active, in the medium long term it could be used to manipulate weather, though this might be tricky, considering how complex is the interaction of the various feedback and feedforward loops involved in what we call weather and climate.