Sunny weather continues for the most part in the Sacred Valley this month. On the Inca Trail, expect it to be dry underfoot on the whole, although a full high season of tramping may still have caused the path to be occasionally churned up. You can also expect little rain and temperature highs of around 68° F (20° C) and lows around 36° F (2° C).
Camping out, nights and early mornings can still be nippy however: pack warm clothes accordingly. If you have any remaining energy after a strenuous multi-day hike to Machu Picchu, down in the jungle below, water levels are low: good for spotting wildlife on river banks.
Crowds & Costs
Crowds are still considerable on the Inca Trail and at Machu Picchu. In fact, for most of the month, these places will still probably be at their maximum daily visitor quotas, although this is more because of it being holiday season in the northern hemisphere (North America and Europe) than anything.
As of next month, visitor levels will drop across the region. Weather in August is still good, but there are fewer clear days on average than in June and July. Overall tourist levels are perhaps slightly down on June, the busiest month, but costs for hotels and most activities remain just as high for the most part.
Where to Go
Sunny weather and crowds in Cusco may incline you towards spending more time out in the countryside, thereby avoiding the masses. There are many incredible ruins in the Sacred Valley, such as the concentric circular terraces of Moray near Maras, or the steep terraces of the Ollantaytambo ruins marking the point where the Spanish conquistadors lost one of their few battles against the Inca.
You will have needed to reserve your spot on the Inca Trail many months in advance to be able to hike it this month, but there are plenty of lesser-known hikes in this part of the Andes: see this article on the best day hikes in the Sacred Valley for ways to escape the crowds.
What to Do
Trekking is definitely the most popular activity in August across the Sacred Valley - and is a surefire bet to evade the most touristy areas if you dislike being amongst crowds. The Salkantay Trek is a good alternative to the Inca Trail if you have energy left or are unable to book an Inca Trail spot.
It is definitely appealing, seeing as the jungle is relatively close and August is one of the best times of year to visit it, to spend some time here too. You could try the Inca Jungle Trek, which gives tourists a jungle experience before taking them to Machu Picchu on the final day.
August is quieter after the Andean mega-festivals that enlivened the region in June and July. Still, a couple of little-known celebrations can make for interesting viewing.
Pachamama Raymi: Earth mother day, or the day in honor of the Incan Mother Earth, Pachamama, happens on August 1. There are celebrations of this traditional Andean festival throughout the Sacred Valley - including, evocatively, at the ruins of Moray.
Willka Raymi: on August 31, this is another honoring of Pachamama, this time in Pisac where particular thanks are also given to the condor as well as to Pachamama. The event is wrapped up with traditional music and feasting.