I have built new front stairs and railings, but broke my arm before finishing the mouldings and priming/painting them. I have a three-day window now before the rains come for the winter. Is there a way to make sure the posts are dry before sealing them now?

I would appreciate any advice,
Rob

Call the local rental store and see if they have a Moisture content meter. Then check this data for your area's emc (equilibrium moisture content).
http://www.fpl.fs.fed.us/documnts/FPLRN/fplrn268.pdf

If the "moisture content" is equal to your area you should be fine to seal.

Other than that I know of now way for sure, except that if it is located where it receives a relativly fair amount of sun and it's been dry the last couple of weeks you also should be fine.

If you take a screw driver and press against the side of the stock and you can squeeze droplets of moisture out of the cells that would be an indication that you are looking at too high of an MC

Alter Eagle Construction & Design