Hatchery winter steelhead are entering the system, and there are probably still some coho around (but they're getting dark). Look for the coho in the canyon below the second hatchery.
Do your steelhead fishing in the lower five miles.
The Kalama flows east-to-west, and the south bank is high. This keeps the water cold, and water temperatures under 40 degrees are standard for winter; bring your sink-tips or your indicators.
There is no river gage on the Kalama, but you can use the East Fork of the Lewis as a surrogate. Just be aware that the East Fork drops and clears faster than the Kalama. If there's a storm, wait to fish here until the East Fork has dropped to normal levels for a couple of days.
For more on December tactics and flies, see the Rivers in General forecast