Barometric pressure

The pattern anglers observe is consistent even though the mechanism is debated. Falling pressure ahead of a front lines up with active, chasing fish and is often the best few hours of the week. The bluebird high pressure day right after a front passes is usually the hardest.

Explanations range from fish sensing pressure changes through their swim bladder to the light, wind and cloud that come with a front doing most of the work. For practical purposes the correlation is what matters.

Falling pressure is the signal to fish fast: spinnerbaits, crankbaits, topwater. Rising post-frontal pressure is the signal to slow down, downsize and fish tight to cover.

The absolute reading matters less than which way it is moving. A steady high over three days fishes better than the first day of that same high, because fish adjust. What they do not adjust to quickly is a sharp change.