Hey Andy,

Good question...

Just because it says a good day, does not mean you will catch a fish...and if it says a bad day does not mean you will not catch a fish...

But hundreds if not thousands of years of watching and recording, shows that some days are better than others.

I have had many days fishing without catching a fish...in fact many days fishing without even getting a bite...But I have never had a bad day fishing. 😊

haha - I've had a few bad fishing days, when just about everything went wrong.

Constant line tangles, lost expensive lures, frozen feet, sudden thunderstorm, forgot my kayak paddle after driving 80km to my favourite spot, fishing rod fell over board and was forever gone, got caught in a current and couldn't get back to shore. One day I even capsized with my kayak due to a leak and lost pretty much all my gear :-)
But those things didn't have anything to do with the fishing times :)

I go fishing on bad days if everything else feels good. Nice weather, good timing for the tides, high season, etc
I caught quite a few fish on bad days. But in general I think the chances are a lot better on good days.

happy fishing!