60 degrees. 50 to 90 degrees F
The type of deck stain used is a major factor. When staining a deck, you have several choices in the type of stain to use. There are transparent stain types, semitransparent stain types, semisolid stain types and solid stains. Transparent stains will soak into the deck boards while a solid stain is more like a paint and will rest on top of the boards.  1 A good temperature range for staining is 50 to 90 degrees F--if wood is too hot to leave your hand on comfortably, then it's too hot to stain. 2  Pay attention to humidity too--the higher the humidity, the longer the drying time. 1 Then start staining again in the afternoon when the sun is lower, staining 2 or 3 boards at a time their entire width. 2  A good temperature range for staining is 50 to 90 degrees F--if wood is too hot to leave your hand on comfortably, then it's too hot to stain. Applying Stain. Deck stain can be sprayed on but is most commonly applied with a brush. Temperature and weather are very important when applying stain. You do not want to apply stain when it is wet or too cold or hot. You want the deck to be clean and dry so that the stain can soak in thoroughly. The temperature should be between 50 and 90 degrees Fahrenheit in the air and on the surface of the deck. If it is too cold, the stain will not dry completely or will be damaged. You will want the temperature to be in the safe zone for at least twenty-four hours. As a general rule, the air temperature for good painting conditions ranges from 55 degrees to 85 degrees. Unfortunately, when applying paint or stain it is the surface temperature, not the air temperature that is important. Air temperature and surface temperature can be miles apart. If a wood deck or wall is in direct sunlight it may well be 30 to 50 degrees hotter than the air temperature. One sunny day in May the air temperature on our test deck was 55 degrees, but the surface temperature of the wood was over 95 degrees. In other words, it was already too hot to stain successfully. Apply stain only at the proper temperature. For most stains, 70 degrees Fahrenheit is the optimum, with the safety range from 50 to 90 degrees Fahrenheit. Stains do vary, so check the label first. First of all, it all depends on the type of stain that is covering the wood deck. There are three types of deck stains out there: Oil-basedLatex-basedWaterborne Although it is okay to stain on top of oil-based and latex-based stains, there is a possibility that the result will be darker than you expect it to be.  Staining Center. Now that you’ve decided to go ahead with your staining project, you will need to take into consideration factors like the weather and time of day when selecting a day for the task. Temperature and humidity can have major effects on how your stain dries. If it’s too wet or cold, the drying time for stains can easily double. In extreme cases, the product will just stay wet until the humidity decreases or the temperatures rises. The Correct Temperatures for Staining Decks. It is important to know the tolerances a new deck stain will allow without hindering its performance. One of the most crucial areas of concern is with air temperature. Temperatures need to be in the safe zone while the deck stain is being applied and for 8-12 hours after. According to most deck stain manufacturers, the air temperature should be no lower than 45 degrees while being applied. This is only an average. Some deck stains need to be applied when the temperature is at least 60 degrees. Check the label on the deck stain you are using. In addition, once the stain is applied the temperature should not drop below freezing for 8-12 hours 1 Apply stain only at the proper temperature. 2  For most stains, 70 degrees Fahrenheit is the optimum, with the safety range from 50 to 90 degrees Fahrenheit. 3  Stains do vary, so check the label first. 
http://homeguides.sfgate.com/staining-needed-deck-69962.html http://paintgurus.typepad.com/blog/2010/07/four-essential-deck-finishing-pitfalls.html http://www.ehow.com/way_5552486_can-stain-deck-frosty-night.html http://forums.finehomebuilding.com/breaktime/general-discussion/deck-stain-cold-temps http://www.answers.com/Q/What_is_the_minimum_temperature_to_stain_a_deck http://www.cabotstain.com/woodcarecouncil/staining-center/staining-s-when-to-stain.html http://www.deckstainhelp.com/deck-staining-temperatures/ http://www.sherwin-williams.com/homeowners/ask-sherwin-williams/staining/exterior-stains/applying/
temperature required to stain a deck