Smallmouth are a great way to have some fun when it's very hot, like it has been here in the north east. If you can tolerate the heat of mid day you can you catch so pretty large smallies. The real brutes are out at first light but then by mid morning they go deep to rest and then the smaller fish come out. Unlike trout they will come back out at mid day and feed in relatively shallow waters, anywhere from 2'-6'. But just like trout they can be extremely spooky when in these areas, so a long cast is vital. As mid afternoon turns to early evening the brutes go back to bed and the smaller fish return. Then as the sun begins to set the brutes return and stay in the feed into the night.
Poppers and sliders can be extremely fun to fish when the smallies are onto the top water game. But at times just one pop and they go running for cover. If this the case it may be wise to use a non popping slider and work it very slowly. Finding the right action for whatever fly you use is a trial and error for each outing.
A fly not to many people will mention for smallies that I use quite often is the fabled and completely deadly wooly bugger. An all black bugger is my go to bugger but at times a brown or olive can be very effective. I like to use the buggers in deep eddies. They can be quite effective on the swing in runs and riffles.
Should you venture out in the heat be sure to have plenty water and a few beers. :) smallies on a hot summer day can be a blast.