The answer is yes , you can and you should! This may come as a surprise to you but it is actually suggested that you have a new custom deck installed during the winter. Not only will the winter season help in the decking process but there is a whole array of other advantages, like winter helps pressurize treated wood. Winter is a dryer season with little to no humidity. This helps the wood stabilize faster and it will dry more evenly.  And also to have your deck ready before the summers.  If you get your deck installed during the winter, by the time it’s barbeque season, your brand new deck will be ready.