Weather affects your exterior wood. Moreover, it also affects your restoration project. For example the wood must be below 15% moisture level to sand or stain. However, Seal-Once deck stain is best applied to moist wood surfaces. Please don't understand that is a controlled moisture level, not rain drops. The entire surface must have identical amounts of moisture. The result is a deeper richer looking stain. I gained this insight from staining hardwood floors -- where it is called "popping the grain". Just a little insight from our years of experience and training.
Additionally, wood staining should only be done between the temperatures of 50 and 90 degrees. Below 50 and the stain will not penetrate or actually thickens up. Above 90 and the stain will congeal or blotch on the wood. While these temperatures are air temperatures, the real concern is the surface temperature of the wood.
You may want to review the attached video to learn more about how weather affects your exterior wood.