Dubbing Combs/Wattles/Lobes?

[chick chicks]

Is there a certain temperature for you need to dub a chickens comb/wattle/lobes? I live on the west coast of Canada so temperatures don't usually get super cold during the winter (doesnt usually get below 0 degrees celcius and if so not for very long) do I need to dub them?

 

[ChickenCanoe]

No.
I'm in St. Louis Mo and it gets to -25C and humid. I've never had hens get frostbitten combs down to -15C, even my Mediterranean breeds.
Roosters are a different story. My big combed roos get frostbitten below -5C, especially when it's really humid.

 

[SD Bird Lady]

I always feel that dubbing is painful and so is frost bite so which is really the lesser evil? I live in South Dakota, US. It gets to -15F many nights (sorry dont have the conversion for that) in the winter and have never had a hen get frostbite but my roo is Brahma and have small pea comb so I cannot say how a breed with a larger comb would be affected.