Actually, API 1104 says the covered electrodes should be protected from changes in moisture content. The work around is easy, store them in water. They cannot get any wetter.
ASME B&PV codes, no mention of electrode storage conditions I am aware of.
in the case of AWS D1.1, there are restrictions as mentioned by my good friend Lawrence, but in light of the New Farm Code (AWS D1.1:2015), the allowance to weld on surfaces contaminated with residual oil, grease, or water, I see nothing wrong with rolling the electrodes back and forth a few time to "dry" the surface to be welded. By the way, this is sarcasm directed toward D1 committee members.
Hate to hijack the thread, but I think it is time to think about starting a protest petition against the changes in D1.1 that permits welding on surfaces that are contaminated. Time for a new thread.
Best regards - Al