rear drum locks up at certain temp.?

[blazer2007]

Pass rear drum likes to lock up sorta at certain temperatures in the winter months. Usually when is close to freezing and is moist out like wet snow . Pass. side likes to grab real quick for a block or so then is fine. Is time to change to winter tires so I would like to fix this. I can,t see any thing weird inside,looks normal. Is on a 89 jeep cherokee but still just a basic drum brake. Brakes are a couple yrs. old but in good condition