Montanans’ are thinking about fly fishing as March rolls in. Most people who fly fish take the winter off. It is darn cold for being on the water and here in Montana, there are many other outdoor recreation activities available such as skiing, snowshoeing, and even ice fishing. But a few warm days and a little sun can raise the water temperature and the interest level of trout and of fly fishers. Many people will nymph fish but there can be good top-water action with midge hatches and blue-winged olive hatches. Of the two hatches, the midges are the most reliable and the least affected by cold temperatures but be ready for anything and dress warm.

Dry flies you might want to have in your box are:
Some of this information is from a favorite entomology site www.west-fly-fishing.com.
The links will take you to their dry-fly patterns.

1. Midge imitations: Sizes 18 and 20 - Brassie, CDC Bubble Brassie, or Copper John to imitate the larvae; try Sprout Midge or Griffiths Gnat if trout are taking adults on the top. Larval patterns are the most effective; dead-drift them on the bottom.
2. Blue-winged olive imitations: Sizes 16-20, heavy in size 18 - Pheasant Tail or gold-ribbed Hares Ear nymphs; CDC Baetis or Baetis Cripple emergers; Parachute Baetis or Sparkle Duns to match duns; and Rusty Spinners if you need to match the final stage. These flies will be very important on warmer days in late February or early March. Look for feeding fish in back-eddies and slow runs. Nymphs should be presented right on the bottom.
3. Baitfish imitations: Matukas, Egg Sucking Leeches, Muddlers, Clouser Minnows, etc. Not the most exciting technique, but if you fishing is slow and you want a chance for a big brown trout, this might be for you.  Using a sink-tip line to get the fly near the bottom, cast, let the fly sink, and retrieve slowly.
4. Standard Nymphs: Size 8-10 - Prince with a Brassie, Copper John, or Pheasant Tail on a trailing leader tied to the Prince's hook bend.
5. Stonefly Nymphs. The big bugs will get active as the water warms up. Sizes 6-10 - Rubber Legs, Kaufmanns Stoneflies, etc. Black, tan, and dark brown are good color choices on rivers with salmonfly, golden stonefly, or Skwala populations.

The first mild day after a cold snap probably won’t be great fishing. Give the weather a chance to stabilize and warm the water for a few of days. Always check river flows on the Montana USGS site. A sudden upward spike will put discolor the water, put debris in rivers and put fish down. Wait for the flows to begin to drop and clear. If it is cold, stay home; but remember, sometimes the snowy days are the warmer ones or it will be cold in the morning and the sun will peak out enough to warm up in the afternoon. You never know, just wait five minutes and the weather will change. Again, take extra clothes in case you get wet and check the state regulations for every fishery.