How long will sour cream be “good” once it’s opened?

Brands vary, but assuming sour cream is stored consistently at 40° F or slightly cooler, it’s usually good for 1-2 weeks after opening. Some experts say 3 weeks.
 
Horizon Organic Dairy guarantees its sour cream for 7 days after opening. Daisy Brand puts shelf life of an opened container of sour cream at about 2 weeks but says consumers should judge the product’s color, aroma, and texture. If the sour cream smells fresh, looks smooth, and has no visible discoloration, it’s probably okay for a little longer.
 
Source(s):
Dr. Robert Bradley, professor emeritus of food science, University of Wisconsin
Food Marketing Institute: “Food Storage Information”
Horizon Organic: “Product FAQs” 
Daisy Brand: Sour Cream FAQs