The boys will be back in 2017 for South Park season 21.

South Park season 21 will premiere earlier than expected. The season premiere will air on August 23rd, according to the South Park website. Since 2013, South Park has began its season in September.
Here are the new episode air dates for the season...
South Park Season 21 Episode Air Dates
August 23rd – Episode 2101 Season 21 Premiere
August 30th – Episode 2102
September 6th – Episode 2103
September 13th – Dark Week
September 20th – Episode 2104
September 27th – Episode 2105
October 4th – Episode 2106
October 11th Dark Week
October 18th – Episode 2107
October 25th – Episode 2108
November 1st Dark Week
November 8th – Episode 2109
November 15th – Episode 2110
South Park Is Renewed Through Season 23
The trolls didn’t start World War III after all. Get over it. That means South Park season 21 is still on track for 2017. For fans looking for some assurance after the season 20 finale, Comedy Central already has a contract in place to keep South Park on air through season 23.
The original contract was set to expire at the end of South Park season 20, but creators Matt Stone and Trey Parker renewed the contract in 2015.
At the time, Comedy Central put out a statement to celebrate the annoucement:
"South Park remains the bedrock of Comedy Central and we are thrilled that new episodes will continue to entertain audiences for years to come," said Michele Ganeless, president of Comedy Central, in a press release. "The series remains as urgent and relevant now as the day it premiered and at nearly 20 seasons in it continues to draw generations of new fans."
In the streaming sphere, South Park remains on Hulu, and will do so exclusively for the next four years. Limited free episodes are available on SouthPark.CC.com.
South Park Season 21 Release Date
South Park returns August 23rd at 10 p.m. on Comedy Central.