Why is it difficult to fish when the sun is out?

It’s hard to say about the sun, but in rainy weather, the oxygen content in the atmosphere is relatively low, and the oxygen content dissolved in the water is correspondingly low, so fish need to go closer to the water to get enough of oxygen, there is a greater chance of encountering your bait. On sunny days, there is more dissolved oxygen in the water and the fish are deeper, so it is not easy to take the bait.

Hope this helps~~