Hiking down to phantom ranch . In the last week of December . Please advice of weather conditions and gear to bring

I refer you to a weather website such as weather.com for typical end of December weather history. You should expect winter weather up at the rim for sure.

I assume you already have a reservation at Phantom Ranch for your trip? You cannot simply show up there without one.

Hitthetrail.com is a great website to help you prepare for that hike in any season.

Totally agree with Hitthetrail.com There is tons of info so take time to read it all. I learned so much for my hike.

I hiked in March (still very much winter) and there was snow on the first few miles of the trail. Yak Trax worked great and I felt stable with them. As we went down it turned to mud and then to fine powder. On the way up, I was actually glad to get back to the snow!!

It will probably be very cold for the first part of your hike but as you go down it will get warmer and warmer so wear layers.

Lots and lots of steps. Hiking poles really helped. I didn't expect so many and didn't train for them. Doing stairs/bleachers would really help.

I have done this hike 20 years ago. My first time i did it in June. I do have reservations at phantom ranch and everywhere . Was looking for info for gear take warm fleece pants or regular pants will do and any other info from someon who has done it in Christmas or new year week

We were in GC last December around Christmas and did not hike. But I will say it was VERY cold and icy. We woke up pre dawn to watch the sunrise and it the temp was in the low teens. Overnight temps were below 10 degrees. During the day I believe it reached the high 20s. Good Luck!!!

I've not hiked the GC in winter but I have elsewhere. My advice is to wear layers. For pants that means

base layer - tight fitting tech fabric - wicks away moisture
mid layer - polypropylene long underwear
outer layer - non-cotton, non absorbent nylon hiking pants. Cotton pants are generally considered a no-no in cold weather hiking.

You can strip down layers as you get down to lower elevations & get warmer.

Footwear
Non-cotton socks
Gaiters to prevent snow from getting in shoes
Shoe spikes (eg Yak Trax) - may only need them for the top 1000' elevation, but you may really want them there, especially if it gets icy while you overnight at Phantom.

For tops, same thing
base = long sleeve tech / tight fitting
mid 1-2 layers
weather proof outer jacket.

and all the necessary hat & gloves. I also wear a balaclava over my head for winter hiking, and strip it off once warmer.

Hitthetrail.com has info on winter hiking and trip reports from people that have hiked to Phantom in winter. You could also look at trip reports on HikeAZ.com

However, layers are essential as already stated. You will experience a big change in temp and one pair of clothes won't suffice for that.

Are you staying in the dorms or in the campground?

Staying in the dorm

You might want to take ear plugs for the dorm. People do try to be quiet but if noise bothers you, you will be glad you have them. A lot of benefit for a small, lightweight item.

Thanks