Yes, "Whenever the sun is shining in your town" is a fragment. It does not complete the thought.
Some examples of a complete sentence would be:
"Where"
The negation of the sentence the sun is shining would be that the sun is not shining.
Shining Sun was created in 2010.
When all Hydrogen on Sun is finished it will stop shining
Sun Is Shining was created on 1999-09-13.
The sun was shining brightly in the sky.
Sun Is Still Shining was created on 1969-11-21.
shining
50% of the sun is always shining on every body in the solar system.
Behind the Clouds the Sun Is Shining was created on 1925-11-10.
There is never a time when the sun isn't shining. The sun has been shining for four and a half billion years and will continue to shine for [it is assumed] another seven and a half billion years.
the sun is like a shining bulb