Sleeping Bag for January - February

I'm going to be traveling around New Zealand for January through February doing as much hiking as possible. My bag is more of a winter bag for the rockies so i'm in the market for something summer specific. I'm trying to pack as light as possible, what temperature bag can I get away with? Any recommend bags? Any info appreciated!

You'd be roasting in full winter bag in Jan/Feb for sure, especially if you're staying in huts. In late Feb/Mar in the south island last year when the weather wasn't for the most part great, I was warm with a lightweight 3 season 700g down bag.