I also walked the Norte Sept 25th - Oct last year. It was beautiful (see my avatar!!)!
Some warm days, which meant swimming at some of the gorgeous beaches. Very little rain and I wore shorts most days.
I would walk this camino again at this time of year in a heartbeat. The weather is a gamble but that's what rain gear is for!!
I was overwhelmed by the beauty on the Norte - the whole way! The food is famously amazing! Some great albergues.
When the split came, most pilgrims walked towards Oviedo and the Primitivo. I had already walked the Primitivo so I stayed on the Norte and really enjoyed that - either way is wonderful.
buen camino!