Found cold spots in exterior wall

[half.baked]

Did a thermal scan last month finally cold enough to get good contrast and found some interesting cold spots on my north facing wall. They're kind of in vertical strips about 16 inches apart. My guess is missing insulation between studs but could this also be air infiltration from the outside? the temperature difference is about 8 to 10 degrees from the warm spots. The wall feels fine to touch and there are no obvious drafts.
The house is 2 story with vinyl siding, built in 1998. Should I be drilling inspection holes to confirm before I do anything major?

 

[Iamshirl]

I saw something somewhere, they drilled small inspection holes in the cold bays low on the wall and used a borescope to see what was there before tearing into drywall
missing insulation is more likely than air infiltration given the pattern

 

[Marney]

Yeah, borescope cameras are cheap on amazon @half.baked