Yoon plunged the country into political chaos last month with the bungled martial law declaration and has since holed up in the presidential residence, surrounded by hundreds of loyal security officers resisting arrest efforts.
On Saturday, thousands descended on his residence and major roads in Seoul a day after a failed arrest attempt -- with one camp demanding Yoon's arrest while the other calling for his impeachment to be declared invalid.
Pro-Yoon supporters massed again in front of his home Sunday despite bitter snow conditions hammering the capital overnight that left it under a white blanket, while an anti-Yoon rally was slated for 2 pm local time (0500 GMT).
"Snow is nothing for me. They can bring all the snow and we'll still be here," said anti-Yoon protester Lee Jin-ah, 28, who had previously worked at a coffee shop.
"I quit my job to come to protect our country and democracy," she said, adding that she had camped outside the residence overnight.
Park Young-chul, in his 70s, said the snowstorm wouldn't deter him from showing up to back Yoon before the warrant expires at midnight on Monday.
"I went through war and minus 20 degrees in the snow to fight the commies. This snow is nothing. Our war is happening again," he told AFP.
The rallies in the cold come as Yoon this week said he was watching protests in support of his rule on a YouTube livestream, pledging to "fight" those trying to question his short-lived power grab.
Yoon faces criminal charges of insurrection, one of a few crimes not subject to presidential immunity, meaning he could be sentenced to prison or, at worst, the death penalty.
If the warrant is executed, Yoon would become the first sitting South Korean president to be arrested.
Blinken wades in
The country's opposition Democratic Party called for the dissolution of the security service protecting Yoon after investigators met a wall of hundreds of security forces preventing access to him.
"The Presidential Security Service has violated the constitution, effectively positioning itself as a force of insurrection," floor leader Park Chan-dae told parliament Saturday.
"There is no longer any justification for its existence."
The service's top officials refused a police request Saturday for questioning, citing the "serious nature" of protecting Yoon.
The Corruption Investigation Office (CIO), probing the martial law declaration, and the opposition urged acting president Choi Sang-mok -- in office for just a week and a party colleague of Yoon -- to order the presidential security service to cooperate.
Late Sunday US Secretary of State Antony Blinken arrives in Seoul, likely to wade into the crisis of a key security ally in talks Monday with his counterpart Cho Tae-yul.
He is expected to delicately encourage continuity with the policies, but not tactics, of the impeached president.
Yoon's lawyers decried Friday's arrest attempt as "unlawful and invalid", and vowed to take legal action.
In scenes of high drama, Yoon's guards and military troops shielded him from investigators who eventually called off Friday's arrest attempt citing safety concerns.
The Constitutional Court slated January 14 for the start of Yoon's impeachment trial, which if he does not attend would continue in his absence.
South Korea's Constitutional Court has up to 180 days to determine whether to dismiss Yoon as president or restore his powers.
Until then, while suspended, Yoon holds the title of president.
Former presidents Roh Moo-hyun and Park Geun-hye never appeared for their impeachment trials.
