Linda Shuck displays a 17-inch Allegheny River smallmouth bass.

Linda and Josh — my fishing guests for the day — were well bundled-up when we left the ramp.

The river valley was still filled with fog, following a clear, cold night, one brightly lit by the full moon. The air was just a couple degrees on the warm side of freezing, and the water had taken a three-degree dip overnight.

Our first spot was the deep side of a rocky flat, one that rapidly dropped from about three feet of water down to around 20. As the boat drifted along in the mild current, my friends worked lures over the flat and down its edge.

Linda scored first, with a fat 17-inch smallmouth taking her soft bodied-jerkbait. Moments after that fish was landed, Josh quickly got in on the action. He’s a master with finesse jigs and swimbaits.

In a matter of minutes, he landed several smallmouth up to 18 inches, both by shaking a light Ned Rig jig down the drop-off, and by slowly retrieving a soft swimbait so it just ticked bottom as it came down the slope. A great start to the day.

And then the fog burned off and the sun came out. It was like throwing a switch from on to off.

During the remainder of the day, we scratched out some more fish — bass and walleye — but the action was slow.

The first boat ride of the morning could be described as bone-chilling. By mid-afternoon, shorts would have been appropriate.

Lacking any significant amount of rain during the past two weeks, the river was clear, with rocks in 10 feet of water easily visible.

While there are exceptions — many in fact —- to the various combinations of environmental conditions, and how they affect fish activity, when you couple clear water and clear weather, and throw in a full moon, it often makes for slow action during the day.

Discounting whatever influence moon phases have on fish and game due to gravitational pull, a bright full moon illuminates the nighttime, providing a good situation for ambush predators like bass to feed after hours.

An Internet search that probed several bass fishing forums on the subject tend to back this theory up. In clear water settings, when the weather is clear, daytime bass fishing around a full moon is often slow. If the water is stained, or the weather cloudy, the effect is not so much. And all of this is during relatively warm weather.

Obviously, fishing at night is an option during the full moon. Just be prepared to deal with fog, and the navigation challenges it presents. The air temperature drops quickly this time of year when the sun goes down. Cold air combined with comparatively warm water is a fog-making machine.

The twilight periods, both morning and evening, are often still good. During the evening, you’re likely catching the beginning of a feeding period; conversely, during the morning hours the last couple hours of activity.

And I’d also suggest being prepared for the exception, when fish bite well despite the many factors that seem to be against you. I’m fortunate to spend as much time on the water as I do, and witness many times when things go better than expected.

Of course, this works the other way, too, when conditions are much like you’d hoped for, but the fish are finicky. Which, speaking for myself at least, is much of what makes whole thing so enjoyable.

If you could accurately foresee angling success, or lack of it, it wouldn’t present nearly the challenge.

Jeff Knapp is an outdoors columnist for the Butler Eagle.