My experience of Northern Peru was quite different then I expect most visitors would have. While most visitors would generally visit Huaraz, Chiclayo, Cajamarca, and Trujillo to visit the beaches and many pre-Incan ruin sites - inclusive of pyramids, I have only been to the city of Piura almost at the very North of Peru, and that was a number of years ago. From what I understand, surfers do go to Piura for the waves. Piura is not quite on the coast, but it is close enough. In the north as we get closer to the equator, it becomes hotter of course, and being in Piura was oven hot and very humid. I remember going for cold showers and coming out of the shower to dry only to be soaked again with sweat in a few minutes. That said it was nice, tropical, and had some beautiful colonial neighbourhoods in the city. Unfortunately as soon as one leaves this fairly wealthy inner city, there are miles of shanty towns surrounding. There was dessert close by on the other side of the city away from the coast, there were also swampy regions, and a number of plantations. The seafood was incredible, the bars laid back, and the ice wine milkshakes were heavenly in the sweltering heat.
A few friends, this time, did travel through the North, but only had a week, so instead of visiting ruins in Huarez and Catamarca, they enjoyed the beaches around Chiclayo and Trujillo, which they loved.