China has recently struggled to shore up the yuan amid hefty capital outflows. Reserves data over the weekend may offer a glimpse of the severity of the challenge.
Analysts are generally calling for a drawdown of around $100 billion, following a decline of $107.9 billion in December.
Reserves plunged by $512.66 billion in 2015, a record drop for the country, to $3.33 trillion, a move attributed in part to Beijing's moves to prop up the yuan.
In addition, China suffered almost $700 billion of capital flight in 2015, according to the Institute of International Finance. Local companies rushed to repay overseas loans as the yuan depreciated, while global investors grew increasingly wary of the country's economic slowdown and Chinese authorities' interventions in the financial markets.
The reserve data due Sunday will be closely watched, even though China's financial markets will be closed for the Lunar New Year holiday for the next week.
"Global markets aren't closed. I think we'll see some contagion effect there if we see a very significant drainage coming through," Steve Brice, chief investment strategist at Standard Chartered Wealth Management, told CNBC's Street Signs. "If there were a trend acceleration we've seen in December and extended to January that would lead to people putting more pressure on the Chinese authorities to be more clear on their communications."