Important things to remember when planning your trip to fly fish the streams of Yellowstone National Park – Weather
Whenever you fish the park, get prepared for drastic weather changes. In June, July and August morning air temperatures at West Yellowstone Montana, for example, will likely range from 39 degrees F. to 90 degrees F. during the day. You need to arrange your clothing in layers so you can shed layers as the day warms but also be able to put on additional clothes if it rains or hails and turns cold.
We were fishing the Yellowstone River on day in mid July when a thunderstorm suddenly appeared and dumped a half inch of ice on the ground. The temperature must have dropped thirty degrees within the hour and the wind picked up as well making it fell even colder. I have seen it snow several time in late August and September, rather often. In addition to layers, make sure you always have a rain coat or jacket, hat or cap with you.
The weather is different depending on the elevation you happen to be fishing which will be different depending on the stream you are fishing. Another often overlooked thing is your hands. They are exposed most all the time when you are fly fishing and if you haven’t been out in the sun and wind much, they could get blistered. It happened to me once which was my first ever trip to the park and I will never forget it. It almost ruined my trip. I fished with very sore and painful hands. You can purchase sun gloves made for that purpose.
Count on the wind blowing. You will be fishing from about 5000 ft elevations up and strong wind can be a problem and 20 to 40 mile and higher gust are very common. That always make the air temperature feel much colder.