I fell and injured my knee four years ago, which caused "traumatic arthritis".
I've noticed that it does react in cold weather, but taking walks really helps. I was told by my doctor that when the pain becomes an issue to apply a warm pack early and an ice pack at night.
The warm pack will increase blood flow to the surrounding muscles and "loosen" the joint so you have less pain while moving around through the day. Ice in the evenings reduces inflammation caused by movement throughout the day and gives it an opportunity to heal and recover.
In my personal experience, applying a heat pack before what I know will be a tough strength workout helps. However, if I'm walking I just begin by not worrying about speed, and then about half a mile into it, it becomes much easier and I get to the speed I want to get to. Ever since I hurt my knee I only jog sparsely - but honestly, I've never really been a "runner" so it works out anyway lol
I recommend walking for achy knees. The more you strengthen your ankles, legs, and back, the more it will take away from the strain on your knees. I would recommend shooting for a mile a day to begin with and then only push it further when you feel comfortable.
Speaking from going through something similar myself. I refuse to let my knee slow me down!