I had similar questions recently about conflicting and hard to find refurbishment schedules. The people on this board were able to help me. The trick to seeing Disney's official information is to visit the map at the link below. Click on any attraction to get the info bubble and then change the date to a date in the future. If you select a date during a refurbishment, the full refurbishment dates will be revealed in the info bubble! It's very convoluted, but it's the best I've been able to find. https://disneyland.disney.go.com/attractions/map/
For Matterhorn, Disney is currently saying it will be closed February 6th, 2017 - April 27th, 2017.
I'm in the same boat. I was really looking forward to riding Matterhorn and POTC because it will be my first time at DL. I guess this just gives me another excuse to plan another trip!