The weather is very safe.

Does the subject want to ask "the reason why the weather is hot, the car has a dull sound when stepping on the accelerator, and the weather will be better when it gets cold"? The change of air temperature leads to the change of mechanical parts' performance. Higher temperature will lead to thermal expansion and cold contraction of mechanical parts in the car, which will lead to relatively inflexible movement between parts and produce friction and noise. When the temperature gets cold, the mechanical parts will shrink, and as the gap becomes smaller, the friction force decreases, thus reducing the noise.