An organ pipe is a cylindrical tube which is open at both ends. The air column is set to vibrating by air flowing through the lower portion of the pipe. The shape of the hole where the air exits affects the timbre of the pipe.
In the diagram the length of the pipe is 0.1 m and the diameter is 0.02 m. The velocity of sound at 20˚ C is 343 m/s.
On a cold day (10˚ C) the speed of sound is 2% slower than on a warm day (20˚ C). How would that affect the frequency?