You can check out Yale locks also but the issue you’re facing has more to do with battery chemistry then the lock itself. You could try lithium 1.5V batteries which has a flat discharge curve and might survive lower temperatures better.
Plus the FE599 tends to shutdown sooner than Yale locks wrt battery voltage.
However do keep in mind that voltage characteristics of lithium 
are different so you need to replace them at a higher remaining percentage than alkaline batteries. For example if you replace alkaline batteries at 30% then the same remaining “capacity” (ie energy) in a lithium battery may report 95%. The voltage curves are flatter and then very steep for lithium so while it will give you a longer battery life, don’t wait for it to get to 30%, it’ll be dead before you get there.