The best hopper fishing occurs in August and early September. They like hot weather, and you will find your best hopper fishing on hot windy afternoons. The only downside with hopper patterns is that they don't work all year round but keep some in your fly box just in case. Banks are the key to successfully fishing Hoppers. Most grasshoppers that find their way into the water's surface are concentrated in the foliage along the banks.
Banks also provide cover and shade for fish during hot summer afternoons.
Thus fish, which move to the banks for cover and shade, are putting themselves in the exact place where grasshoppers are most available. On large rivers, grasshoppers should be cast as close to the banks as possible. This is more important in streams where banks are slightly undercut and where vegetation hangs out over the water. On small streams, trout often see grasshoppers all across the water and will be willing to take an imitation in the middle of the stream. Investigate or range of hoppers.