Pradosh Vrat comes double consistently and it falls on the thirteenth Day or Trayodashi date of each month. This time in December it is falling on the ninth. It will fall on a Monday, henceforth it will be called Som Pradosh. Assuming it were on Tuesday, it would be Bhaum Pradosh and on Saturday it would be called Shani Pradosh.
Pradosh Vrat is propitious to get the favors of Lord Shiva. On Pradosh Tithi, assuming you love Lord Shiva through custom, you would even get the gifts of staying admirably and Bholenath will achieve every one of your desires. This time on 9 December, the favorable season of love is from 5.25 in the evening to 8.08 around evening time.