No, you would not hear an echo on a hotter day if the distance between the sound source and the reflecting surface remains the same. The speed of sound increases with temperature, meaning the reflected sound would reach you sooner, potentially before you could distinguish it from the original sound.
Explanation:
Echo Formation:
An echo is heard when the reflected sound wave reaches the listener after a noticeable delay (at least 0.1 seconds) from the original sound.
Speed of Sound and Temperature:
The speed of sound in air increases as the temperature increases.
Impact on Echo:
If the distance between the sound source and the reflecting surface remains constant, the faster speed of sound on a hotter day would mean the reflected sound would arrive at the listener sooner.
Reduced Echo Duration:
Because the reflected sound reaches the listener faster, the time difference between the original sound and the echo would decrease.
No Echo Heard:
If the time difference falls below the threshold of 0.1 seconds (the minimum time needed to distinguish the echo), you would not hear a distinct echo.