Afternoon Shiver

It is meeting time.
Distracted by passers by,
Listen and observe.

I observe this one
Coming and going again.
The meeting goes on;

This one goes again.
My body soon shivers hard;
No explanation:

I’m indoors, it’s warm;
Winter has yet to strike here.
But still I shiver.

She returns once more,
A sweater now adorns her.
Shivering explained?

Care to share your thoughts?