Larry L wrote:

I've been lucky enough to spend a fairly large amount of time in Idaho and
Montana, over the years, in the times between June1st and Sept 1st.

I've heard, but never experienced, good things about the fishing in April
and Sept.


My experience over the years in CO (I know it's not MT or ID):

The two months you mentioned are two of my favorites. Rivers are not
crowded and the fishing is VERY good.

April is prerunoff. You CAN get runoff in April, but that's VERY
unusual. Prerunoff fishing starts usually at the end of February. It
starts slow with midges and some small BWO's stirring some fish. Then as
the water warms, the fishing gets better and better until it becomes
OUTSTANDING - then runoff starts.

September is a good month. It's better, IMO, later in the month than
earlier. The cooler weather starts to cool the rivers and this gets the
fish stirring.

In terms of weather, April is a wet month and you can get quite a bit of
rain and snow. September is generally dry. Temperatures both months are
usually pleasant.

Locally there are no "famous" hatches during either month. April will
get some very good BWO's and some caddis are about. May here in CO
brings out a heavy caddis hatch. The first part of September will still
have some good Trico activity but that fades with the cooler weather.
BWOs, and caddis are about but no heavy hatches. (When fishing the
Bighorn this year in September, we had what was probably the heaviest
caddis hatch I've seen.)

If I had to choose between the two, I'd pick September. Fall is my
favorite time of the year. The weather is usually great, the fishing is
generally good, and the light and the changing leaves are beautiful.

Willi