The basicsTechnically speaking both Rims of GCNP are openAlmost all of the the facilities on the S.Rim are open in winter But a few hotels do close down On the N.Rim all l the facilities and the road leading to them are closed in winter However if you wanted to drive to Jacob Lake AZ , park your car and then snowshoe /ski/hike into the Park the NPS would let you do it .If you wanted to spend any time camped below Rim the NPS would require you to have a Backcountry Use Permit When you drive cross-counrty in winter you absolutely must be prepared to spend a night or two living out of your vehicle .You can do everything right and if a semi or two gets sideways ,blocks an interstate and closes it for a couple of days being prepared can be a life saver Let the weather be your guide and try not to get too enamored with one route But rather adjust on the fly to be where the bad wether isn t Realotically in winter this is a 4 day trip ..each way This would be my ideal routing ...and Yes I ve driven it in winterCome over the GW and take I-80W to tyhe junction of I-76W @ JulesbergNEI-76W to I-70 at Denver Stop either an hour east or a half hor west of DenverNext day Pop this intomapquest or whatever just ignore their timesDEN Moab UT Hanksville UT Torrey UT Escalante UT MountCarmel JunctionUT Hurricane UT Colorado City AZ Jacob Lake AZ GCN FLG Tuba CityAZ Mexican Hat UT Cortez CO Walsenberg CO ABQ then I-40 E to I-81 N to I-78E and thru the Holland tunnel.Since i just sent you thru six NPs you will need an $80.00 National Parks Pass get it when you visit Arches NP in Moab UTWhne your west of I-25 get into the habit of getting gas before you really need it My MO for doing long road trips is to hit the road by 5:00AM do a quick 150-200 miles and then grab breakfast Safe trip and enjoy the West
http://www.nps.gov/grca/index.htmThis site will answer a lot of questionsThere s also a FAQ list and Contact Us linkLooks like they are closed in the Winter.. But the place is huge I didnt read all of it. Ive been there several times, but always summer.