Solid Hardwood, Engineered and Laminate Flooring - hardwood and high humidity

My sister just bought a house that's built in a floodplain. The basement isn't wet, but it is damp and she has a dehumidifier running. She wants to install a new hardwood floor upstairs and was told that the wood would have to acclimatise in the house for 6 months before installing.
This sounds excessive to me. Any thoughts?

The structure needs to dry to the regular living conditions if it has been unattended for a while. A floodplain and hardwood are probably a recipe for disaster without properly waterproofing the home first.

Although a "vapor barrier" won't be effective (you will be driving 10,000 holes in it), placing a layer of 15# felt seems to have a good effect in keeping the migration at bay. That will leave the room humidity and temperature to deal with the flooring. 6 months is a little long. You may want to consider engineered wood, which is somewhat better at handling fluctuations. I am taking delivery tomorrow on 825 sf of flooring, but I can't begin laying it until sometime Thursday to give it time to acclimate. Others may have different views, so it is important to check back, as others in your area may chime in.

You may want a little more acclimation time than two days. Acclimating a wood product has little to do with temperature and everything to do with moisture content. The wood should be acclimatized to the moisture level of the existing floor and the relative humidity of the structure. You hay want to get a moisture so you know when the floor and floor covering are close enough in moisture content to be installed.

You hay want to get a moisture so you know when the floor and floor covering are close enough in moisture content to be installed.

A moisture meter is what he is recommending. Lignomat makes a 100$ miniligno that is perfect for your needs. Ebay may have one cheaper.

Thanks for all the replies guys