As far as temperature goes, high temperatures are most important.
When the surface temperature gets too high for the comfort of trout they move to deeper water where it is cooler or where a cool tributary enters.
Most of the streams I fish are not deep enough to have cooler depths so if the temperature is above about 20°C, trout are less inclined to feed or even stop altogether in the afternoons of hot days.
They are best fished early and late.
Also, trout being returned to warm water take longer to recover and should be held upright until they swim away.
In still waters when it is warm it pays to fish into deeper water and the fly or lure should be allowed to sink before beginning the retrieve.
If you hook a fish in deeper water it has to be brought through the warm shallows to land so when returning it, release it as close as possible to deep water.
Taking all the above into account, small streams are not a good option except early and late in the day.
The same could be said for fishing the shallows.
Larger rivers such as the Taieri, Mataura and Pomahaka should be in good order for the weekend.
The last factor that influences catch rate is the prevailing atmospheric pressure.
The best is stable high pressure, then rising pressure and the worst is rapidly dropping or very low pressure.
None of these influence whether or not I go fishing, but temper my expectations.
Murray and I fished the dams on the Maniototo on a hot day last weekend and we saw very few rises.
The fish we caught took a damsel fly nymph that was allowed to sink for at least half a minute.
My best fish took that nymph when I let it sink in a deep channel for nearly two minutes and took at the beginning of the retrieve.
Do not think fish cannot be caught if there is nothing rising. Most trout feed most of the time, especially bigger fish as they need more food to maintain themselves.
Smaller fish need less and feed in short bursts, which explains why we catch more big fish than small fish.
Wednesday ticked all the boxes when I fished the Pomahaka — high pressure, water temperature 17°C in the morning, and water slightly misty but low.
I was given a dose of false optimism when I caught four fish in the first 100m that I fished.
I was feeling a bit more realistic when the fifth fish was caught an hour later.
It ended up being a good day with trout being caught on emerger and hare’s ear nymph. Surprise, surprise!
