Question

Explain why smell of petrol in the petrol station is noticed more in summer than in winter?

Answer 1

It is because smell dissociates more when it is hot or warm.
Like the smell of hot food is noticed more than of cold food.

Answer 2

In summer the air is dry, the air velocity is more.  The diffusion of gases is proportional to the temperature (with some power).   The diffusion depends on the velocity and the average velocity in gases is proportional to temperature.

So in dry summer with less humidity, the smell propagates more.