Overcast cool weather leads to better fishing in general. The key on streams IMO, is knowing where the fish are. They are not stagnant. They move into different lies as the weather changes. Fish care about 3 things. Safety, food and oxygen levels. Those 3 things are influenced by flow rates, sunshine vs overcast, biomass of insect hatches which is correlated with weather etc.
I was on the middle Provo Monday. For the last month I’ve fished there at least once a week and I know where the fish are. Two days ago the numbers of fish I caught in the usual lies was way off. Our weather is beginning to change so I changed up just a little and fished deeper, and a little faster more oxygenated water. Using the same flies, i started catch lots of fish. It isn’t the fish weren’t there they just moved to a place where their safety, food and oxygen was better.
Think like a trout.