When it comes to brakes, temperature is an important factor. Brakes can start working if the temperature is as low as 0°C, but their performance will be reduced when temperatures drop below that level. Generally speaking, brake systems tend to become less effective at temperatures lower than -20°C and may even fail completely if the temperature drops too far. This means that in extremely cold weather, drivers have to be extra cautious with their braking since they might not be able to rely on their brakes to work properly or stop them in time. In addition, heat also affects the performance of your brakes; if the brake system (including pads and rotors) gets too hot due to excessive use over a short period of time, they won’t function optimally either. So while there isn't a specific temperature at which all brakes will stop working completely, it's best for drivers stay aware of how different conditions (such as cold or heat) affect their vehicles' performance so that they can make adjustments accordingly.