It's a cold, clear day here in Ellensburg, and with daytime air temps in the teens and overnight lows in the single digits, it's not a bad idea to hold off on fishing the Yakima for a few days. It looks like we will see a big warm up by the middle of next week, which should help get the bite going again, as well as make it a heck of a lot more comfortable to be on the water. Nymphing a stonefly/worm/midge combo should be good in the slower runs and buckets, and if your guides aren't icing up too bad, swinging a streamer should move a few fish as well. If streamer fishing is your game, think small and subtle with your patterns and remember a slow swing will outfish a faster retrieve when the fish are lethargic.
Rocky Ford has been fishing well, even through the cold weather, and if you have a serious case of the shack nasties to kick this weekend, "The Ford" is your best bet for a bent rod. Nymphing San Juans or egg patterns has been good, as well as the always productive olive scud. If there is some cloud cover in the forecast, don't forget your small dry flies as there are both BWOs as well as midges around, and when the fish are looking up, this is one of the best places in west to catch a fish on a dry fly in December.