When stain fails to dry or adequately absorb into wood fibers, a number of contributing factors could be to blame. To prevent this occurrence, follow the proper finishing guidelines.
If you apply stain to a deck when the temperature is too low, the finish may remain wet for long periods of time. For best results, wait until the temperature is above 60 degrees Fahrenheit; never apply stain to a deck when it's below 45 degrees outside. Humidity can also prevent stain from drying. Don't apply stain to your deck when the air is thick with moisture.
Improper application methods tend to lead to slow drying times. Be sure to wipe the wet stain from the deck after you've brushed it on. Use disposable rags to sop up areas of pooling stain. It doesn't take but a few seconds for stain to permeate wood fibers; you don't need to leave it on the deck for long periods of time.
Some decks are composed of lumber treated with chemicals that protect it from decay and infestation. These decks contain moisture that prevents stain from absorbing into the interior fibers. If the stain isn't drying on your treated deck, dry it with old towels; then wait six weeks for the deck to dehydrate.