Peru weather in early September?
 

I'm trying to get a sense of what type of weather to expect in Lima, Cuzco, the Sacred Valley and Machu Picchu this time of year. From what I can tell (and for some reason foreign weather forecasts are often inaccurate on the web), Lima has highs near 70 F and lows around 60. Cuzco's highs seems to be only a few degrees cooler, but they get cold nights -- into the 30s.

It seems like the Sacred Valley and Machu Picchu are a bit warmer (lower elevation) that Cuzco.

Are these reasonable expectations? If so, it would seem there's no reason to bring shorts and that even short-sleeve shirts are dubious. And I guess a couple of light layers would make sense for Cuzco's temperature swings. Correct?

Thanks for the packing help!

Your temp estimates for Lima are pretty accurate although the Peruvians, like the rest of the world, talk Celsius, so expect around 15C at night and highs of around 20C. There will probably be a lot of low marine cloud which may or may not burn off in the afternoon, familiar conditions if you know coastal southern California in June. Humidity levels are high day and night.

For the other sites you're pretty close as well. You should definitely have a pullover or fleece for Cuzco and the early morning train ride to Machu Picchu. You should also be prepared for some rain. September is a "shoulder" month in the Andean cordillera, during the transition from the dry season to the rainy season. If my past experience is any guide conditions will be more dry than wet but the rains are variable from year to year, so it doesn't hurt to take goretex with you.

As far as shorts are concerned, even in the jungle many Peruvians are more formal than North Americans, and favor long pants. In Lima I can practically guarantee that you won't see anyone wearing shorts, even if you go to the beach (because there will be nobody there).

Thanks! That's exactly the info I was looking for.

So I'll be leaving the shorts at home. The short sleeve/long sleeve issue seems tougher. Just a matter of personal preference, I guess?

Yes. I'd take both just in case. It may be warm enough at MP that you will want short sleeves.

Just an update from my September experience. Lima was quite chilly -- coat needed even in daytime. Sacred Valley significantly warmer, no coat needed (except perhaps very early morning, late night). Cusco almost as warm as Sacred Valley, except a little cooler at dawn.

The Limenos told me this is "record cold," and that Lima should be warmer than the Sacred Valley, so maybe it's just odd. But bring a coat!