prakṛtyā by nature, śītalasparśaḥ cold touch, sāmpratam at this time, himaviddhaśca hit by snow, paścimaḥ vāyuḥ the west wind, kālē at this time, dviguṇaśītalaḥ doubly cold, vāti blowing.
The west wind which by nature feels cold at this time blows doubly cold, hit by snow.