The festival of Kali Chaudas is celebrated on Chaturdashi Tithi during Diwali. This year Kali Chaudas will be observed on Wednesday, November 3.
According to drikpanchang.com, Kali Chaudas is also known as Bhut Chaturdashi and is mainly observed in Western states, especially in Gujarat.
Kali Chaudas is celebrated on Chaturdashi Tithi of Krishna Paksha of Kartik month of Hindu Lunar Calendar.
The day dedicated to Goddess Kali and is observed with great devotion. It is believed that Goddess Kali killed the wicked Raktavija on this day.
Kali Chaudas timings for Mumbai:
Kali Chaudas Muhurat - 11:57 PM, Nov 3 to 12:47 AM, Nov 4
Chaturdashi Tithi Begins - 09:02 AM on Nov 03, 2021
Chaturdashi Tithi Ends - 06:03 AM on Nov 04, 2021

(Date & Time Source: Drikpanchang)