Honestly, yes—it can crack, but it is not a given. I have seen cheap concrete benches break apart after one bad winter, while well-made ones sit outside for decades without more than minor surface wear.
The real problem is not just the cold. It is water. Concrete is porous, so it absorbs a little moisture. When the temperature drops, that water freezes and expands inside the tiny pores. Do that over and over, and the surface can start spalling or forming hairline cracks. If the bench has larger voids, or if water gets into an existing crack, the freeze-thaw cycle can wedge it open further.
There is another issue people overlook: the ground under the bench. If the soil freezes and heaves unevenly, the bench may no longer be supported evenly. A rigid concrete slab or bench can crack under its own weight when one end lifts and the other does not. That is why a proper base matters just as much as the concrete itself.
So will yours crack? It depends on a few things. Quality of the concrete matters a lot. Air-entrained concrete made for outdoor exposure handles freeze-thaw cycles much better than standard mix. Reinforcement also helps. If there is steel rebar or mesh inside, the bench can hold together even if small cracks appear. Drainage is huge. If the bench sits flat on wet ground with no gravel base or gap for water to escape, the bottom stays damp and becomes more vulnerable. Sealing helps too. A breathable concrete sealer can reduce how much water soaks in.
If you want to protect a concrete outdoor bench through winter, there are a few simple steps. Lift it onto pavers, gravel, or a slightly raised base so it is not sitting directly in soil. Keep the area around it free of standing water. Check for small cracks in autumn and fill them with concrete crack filler before water gets in. If you live in a harsh climate, cover the bench with a breathable cover that sheds rain and snow, but do not wrap it in plastic tight against the concrete because trapped moisture can make things worse. If the bench is movable, storing it in a shed or garage during the worst months is the easiest solution.
The short version? A concrete outdoor bench can crack when the ground freezes and thaws, especially if it is poorly made, badly supported, or sitting in wet soil. But if you start with good concrete, give it a stable drained base, and do basic winter care, it can survive many freeze-thaw seasons without serious cracking.