Thats great!! Having someone to train with helps you keep to you goals and is a lot more fun...so ive heard..
Upper body strength training is great, you'll be in tip top shape for next year when the warm months come around, and training in the rain is still very do able, just move slower and be more careful, it actually helps a lot, if you train in the rain all the time, then when its dry and warm, you should be great