Mt Taranaki is one of NZ’s wettest spots, and frequently cops snowfalls, even in summer: weather on the mountain can be extremely changeable. Ironically, New Plymouth frequently tops the North Island's most-sunshine-hours list. Expect warm summers and cool winters.
Over in Whanganui the winters are milder, but they’re chillier on the Palmerston North plains. Sunshine is abundant hereabouts too – around 2000 hours per year!