Pradosham is a significant day to worship Shiva and Parvati. Pradosham literally means the removal of sins.

Pradosham is a significant day to worship Shiva and Parvati. Pradosham literally means the removal of sins. Trayodashi/ Pradosham is the thirteenth phase of the dark or bright moon, is the time designated for Shiva to remove the bad karma of people. Lord Shiva drank the Halahala, poison that was churned up during Samudra Manthan on Pradosham.‪ Shiva and Parvati are in a propitious mood during the evening twilight on the Trayodashi day and hence are easily pleased and grants whatever that a sincere devotee asks. It is believed worshipping one Pradhosham equals going to temple for 15 days, worshipping 11 pradosham equals seeing one Kumbhabhishekam. No rebirth for those worshipping 120 pradhosham. Shani Pradosham is When 13th Moon day falls on Saturday and its is the supreme level for worshipping Shiva. Lord Shiva has more influence over Shani Dev on this day and can cause Saturn to loosen or release some of the karmic bonds that limit us. To overcome the bad influence of Shani, devotees observe a fast on Shani Pradosh and offer prayers to Lord Shiva during the day. Tomorrow is Shani Pradosh, worship Shiva wholeheartedly and chant his mantras, along with Shani mantras on this pradosham day to free yourself from all your sins.
Jai Shani Dev ~ Jai Ardhanarishwara!