It depends on what you want to accomplish with the pruning. For shrub roses, which are usually pruned to remove dead/dying wood and for shape, the only temperature that matters is when it is cold enough for damage to travel down a fresh cut. That *should* be well below 20 °F. The *should* is because it will vary depending on the hardiness of the rose, and I would think that roses damaged from pruning at that temperature would have trouble surviving below zero temperatures intact.

The usual frost and freeze information has about zilch to do with any established hardy plant. They are going to grow when they are going to grow, and if they consistently too stupid to know when they are supposed to grow they are too stupid to belong in your yard. The reality is that, particularly on the east coast where spring comes slowly, it's rare for the plants to get so out of sync they have problems.

Roses are hardier than we think and can handle the average spring frost with little if any damage.
In my area, our last average frost date is May 15. I prune from Mid March into April. Except for that Easter freeze last year, I've not had a problem. Last year I lost no plants . I just had to prune off the freeze killed growth.
Mom Nature takes care of her own. New spring growth contains lots of sugar which is a natural antifreeze that protects against the average frost.
Yesterday I picked up 160 hardy rose cuttings. They're in my unheated greenhouse. While day time temps can reach 70-80 on sunny days, night temps fall close to that of the outdoors. None of my cuttings in the unheated greenhouse suffered damage during last springs Easter freeze. With night temps falling to the low 20s and teens now I'm not concerned that the greenhouse roses will suffer any damage. Don't worry about pruning in your area now. Should you experience a prolonged late freeze like last year, cover the bushes with upside down buckets, rose cones, or lay old sheets/tarps/blankets over them.

The old adage of pruning roses when the forsythia blooms seems to work well for me in SE PA.

if they consistently too stupid to know when they are supposed to grow they are too stupid to belong in your yard.
LOL, Mad gallica. That gave me a good laugh!

Carla

The forthysia blooming is a guide, not written in stone. A warm winter can mean the forthysia might bloom a month or more before it would otherwise. While I prune in late March to mid April in my area, I would not prune in mid February just because the forthysia is blooming

Karl is right about the "forsythia signal". While it may be fine as a general guide, it is not a completely reliable biological "clock".

It would be better to familiarise yourself with the weather pattern in your area. I usually prune after the risk of any prolonged hard freezes - where we live, that's usually in March. Forsythias may or may not have started blooming by then.

The above applies to spring pruning. Pruning to remove old, diseased, weak, damaged and unwanted wood is done all year round in our garden, weather permitting. (I am essentially a fair weather gardener!)