I f you are concern about the weather any time is good i think, every region of Peru has its own weather and micro climate, when in some area is cold in another is warm or hot. It depends what will be your route. For example at this time is high season Peru in general, but in Lima is some cold and humity , winter but not so cold but very humid , the minimum is 13 C , in North Peru is around 30C. In Cusco and Macchu PIcchu are differences too even when both are in same province, Cusco city is inthe andean mountains so in this time as ussually in all all andean cities in cold in nite and in early morning and hot in day. Macchu Picchu is near the rain forest or jungle and lower and Cusco city so if you leave cusco in early morning you will need wear warm clothes and below fresh clothes when you arrive to Macchu Picchu, so be ready for all if go to Peru..... ;)
