Tex: To answer your question, notwithstanding the info provided by pnorth about Maui: Each island is unique and has its own weather patterns (tho they do share traits in common due to their proximity), so your question is valid and should be addressed.
If you are only going to be staying in the Honolulu area, yes, Waikiki will be warm enough for you to lay out - especially if you're coming from a colder climate. I assume from your moniker that you're from Texas, so depending on the region in Texas you're from, it could be a nice change. It can be damper and the waves will be larger during the winter, but for the most part, Waikiki beach will buffer most of the heavy wave action, especially the lagoon area of Kahanamoku beach.
Rain is not constant, tho you do have to switch into "Hawaiian mode" and expect to have 2 to 3 minute showers from time to time. But, if you're swimming in the ocean and it rains - does it matter?
Since Honolulu is on the south side of the island, the beaches should not be as affected by the big swells as you will find on the north side. However, with that said, high surf can occur anywhere on the islands, so staying close to the beachshore would be advisable. Another good beach during this time would also be Hanauma Bay on the east side, tho the same caveats apply. For a show, hit the north shore and see the size the waves there -- definitely NOT for swimming!
For more information, you may want to check out the following websites: www.gohawaii.com
Have a great time. Hawaii is beautiful any time of the year.