What season was it when the necklace took place

The majority of the women at the party were wearing furs. Madame Loisel was shivering from cold because she wouldn't put on her coat in front of the other women. From this, we can infer it is winter.

She felt this and wanted to run away, so she wouldn't be noticed by the other women who were wrapping themselves in expensive furs.

They walked down toward the Seine in despair, shivering with cold. At last they found on the quay one of those old night cabs that one sees in Paris only after dark, as if they were ashamed to show their shabbiness during the day.