Is it okay to store lumber outside?
Whenever possible, wood should be stored indoors in a cool dry location. But if you must keep it outside, it’s best to have it covered at all times.
How long can you leave lumber outside?
Wait it out. Wet lumber will naturally dry out if given enough time. If the outdoor temperatures are above 60 degrees F, it usually takes about 4 weeks for moisture content to decrease about 4%. It might take 6-12 weeks for a 4% drop if its cold and rainy.