Its 95 degrees in Portland today as we are the in the dead of summer. People are having BBQ's, pool parties, or maybe just relaxing outside with their favorite beverage. So, what's the best wood for outdoor furniture? Does it matter? Oh yes. It matters.
Most wood species are going to be susceptible to moisture and bugs - the two major enemies of wood. Both can cause rot, unusual twisting or warping, and general decay. You don't want to be thinking of the word decay when you're enjoying your new outdoor dining table.
Cedar and Redwood are probably the two most common woods used for outdoor furniture. Cedar is very common with planter boxes, fencing, and chairs. Redwood is also a great wood and does well against moisture and decay. Both woods are softwoods so they are light and easy to move around if you feel like rearranging things anytime. The downside of a softwood is that it won't hold up as well to wear and tear.
For something more substantial, white oak is an extremely dense hardwood. The density makes it resistant to bugs and moisture as well as heavy. Dining tables or other furniture that you want to be extra solid would do well being made from white oak. A white oak dining table with the proper finish would be an amazing outdoor addition that would last for years.
Finish is another thing to consider. You really want to use a finish that is made for the elements such as Spar Varnish or Aqua Spar. I believe that finish was originally made for ship masts. You can imagine how much wind and water a ship mast would take while out at sea (or even docked).
So, if you're thinking you'd love an outdoor table made of walnut or maple, I would suggest going with white oak and then applying a stain to achieve the look you want.