Adjustments for low temperature should be made. If the adjustments are not made then be prepared for certain terrain features to trigger GPWS warnings. The Canadian Approach supplement for Jepp charts have a very handy correction chart. I keep it with my Whitehorse Yukon plates which we often use as an alternate. The deviations get greater with height above the altimeter source. A 2,000 foot clearance, normal temperatures, in mountainous terrain could very well become
only about a 400 foot clearance under extremely cold temperatures.