When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

An echo is heard when the time for the reflected sound is heard after 0.1 s

Time Taken= Total Distance / Velocity

On a hotter day, the velocity of sound is more. If the time taken by echo is less than 0.1 sec it will not be heard.