Oh snap, I just found this study (https://www.mdpi.com/1996-1073/14/17/5343) that has a focus on hempcrete in colder climates, and one of the test sites was Winnipeg, Canada!

It definietely seems like hempcrete can be used in colder/wetter climates but it's probably more beneficial in warmer/drier ones. I didn't see much about exact temperature ranges, but the study did show that hempcrete does a better job of cooling a space than warming it.