So I would expect stronger water vapor effects in summer than winter, and stronger in daytime than at night, though clearly not by much. (realclimate.org)
Cloud cover and other water vapor effects for the future are completely unpredictable. (realclimate.org)
In fact, as the atmosphere warms, the «atmospheric window» tends toward closing (particularly because of water vapor effects), and excess escape through this window can't account quantitatively for the reduction in stratospheric temperatures. (realclimate.org)