It would get damaged at about 20-25 and will be killed at 18 or so

especially on the east coast being a wetter winter than they like...

Yeah, Im going to say they can handle about down to 20F. Some are grown well in the southern parts of the outer banks of NC but thats a mild zone 8b maybe even a borderline 9a. I think lower than 20F will kill it, but they can definitely handle below 30F (they were not damaged in many parts of central florida last winter from the historic freeze which brought temps to the mid to upper 20s a few times at night).
They dont like wet and cold. Thats a very bad combo for most palms and a very common combo for areas in the east during the winter months.

There are other palms and even other phoenix palms that can handle lower temps and give you a similar effect. I think a pindo palm would the the next best thing for a more cold tolerant version of that type of effect. But I think you can get a phoenix canariensis to survive the winter with some protection. In a zone 8 I dont think your temps drop below 20 too often so just protect it when temps are forecasted to drop below 25F if you really want one.

Good luck!
-Alex

where do you live VOBGRO? if your on the west coast you could pull it off with some protection in a zone 8a. i dont no much about east coast growing but i would trust their judgment but if you you live on the west coast i would say cold hardy to 16*f a bit lower if its a brief cold spell! but for sure it will fry & turn brown but it should come back come spring! & if its in a good position in your yard where it gets hit by the morning sun.

West of Jacksonville through Lake City you will find CIDP planted that have been there a long time. (very large specimens) Temps in Northern Florida have been known to drop into the upper teens on occasion. Florida's rebound temps might make this area an exception but in my experience the CIDP can withstand occasional Zone 8b temps with no protection and still look very good.

CIDP survived the record-breaking cold winter in 2010 in Florida with no problems. Temps here were 28 for several hours on more than one occassion. Royal and coconut palms were severely burned, but all of the phoenix palms on my property were unaffected. They are definitely cold-hardy palms.

I dont think anyone can give a exact temperature that will kill this palm because many factors are important one is moisture and another is the duration of the cold (which is also a major flaw in using USDA zones). I think the Duration of the cold might even be more important than moisture. I can say that if this palm sees 20F no lower and no higher for 48 hours, it will be dead, but a short duration of 20F and it will be fine. If it sees 15F once every 10 years and temperatures dont get cold for the rest of the witner (and warm up from the 15F quickly), it would probably survive. I think that if it sees lower than about 10F (even a short duration but without protection) and its a gonner.

Good luck!
-Alex

I live in Dallas,TX