June has arguably the best weather of any time of year along the Inca Trail. This month is the closest you will come to constant sunshine and cloudless blue skies in the Andes; rain is fairly rare.
Be aware that despite this, the valley in which Machu Picchu sits sometimes seems to have its own special microclimate, and when you arrive there after three full days of hiking, you should still be prepared for mist swaddling the ruins in the morning even at this time. Generally, you’ll get more sunshine, but colder temperatures (especially at night, for those camping out on the Inca Trail) with highs around 66° F (19° C) and lows around 34° F (1° C).
Crowds & Costs
Crowds are approaching their maximum levels in and around the Sacred Valley this month. If you want to book the Inca Trail for this month, or the other high season months of July and August, you will need to do so half a year in advance. Be aware that on every day from June through August, numbers on the Inca Trail are at their maximum.
Journey on any train from Cusco or Ollantaytambo to Aguas Calientes, the station for Machu Picchu, will also require booking several months in advance. The busiest time in June (and in the year) is Inti Raymi, the Inca Festival of the Sun. All June sees hotels and bookable tours at some of their highest prices of the year, but on Inti Raymi costs, particularly for hotels, increase even more. Rooms are hard to come by at this time too.
Where to Go
Cusco and Sacsayhuamán are the places to be this month for Inti Raymi. However, if you can time your Inca Trail sojourn to coincide with arrival at Machu Picchu on the morning of Inti Raymi, this is also pretty special. Experiencing the biggest day in the Inca calendar at the most legendary Incan site is an unforgettable experience. To escape the crowds at Machu Picchu and Cusco, some other Sacred Valley towns such as Pisac or Ollantaytambo can provide a welcome respite in June.
Make the most of this brighter, chillier weather in June through August and head for a dip in the hot springs of Salinas near Maras (colder temperatures mean getting in is more inviting, whilst the sun will help dry you off afterward).
What to Do
Nature-lovers are pretty contented with a June trip along the Inca Trail and surrounding Sacred Valley. Animals come out more to enjoy the sun at this time of year. One beautiful addition to the birdlife around this time is the Andean condor, most commonly seen from now until the end of December, in craggy upland areas. Animal-wise, watch out for the rare spectacled bear: South America's only bear, and the species on which Paddington Bear was based!
In the jungle too, the sun has an effect. Falling water levels in the jungle close to the Sacred Valley mean animal sightings on the riverbanks are increasing, and birds are more commonly seen from canopy viewing platforms because they like warming themselves in the sun.
June continues to be a great time for hiking and for outdoor activities of almost every kind. See here for some of the best short hikes in the Sacred Valley near Cusco. The one exception to this is probably rafting, where water levels are generally lower, unless you are wanting to raft the Río Apurímac in which case June is one of the best months.
The other thing to do is attend a festival: festivals do not come better than Inti Raymi, celebrated in and around Cusco.
Cusqueña Beer Festival: Peru's most popular beer, Cusqueña, has an entire festival dedicated to it in the city where it is made, Cusco. Held during the first week of June, accompanied by lots of live rock and salsa.
Corpus Christi: This solemn festival of religious devotion takes place on June 11 in the central squares of towns and cities in the Sacred Valley and across Peru.
Inti Raymi: This, the main celebration in the Inca and Andean calendar, is the festival of the sun: traditionally honoring the shortest day of the year in the Andes and when the sun is furthest from the Earth, June 24. The Inca Empire feared the damage a lack of sun would have on their crops and therefore gave homage to the sun on this date to ensure its return.
The Incan God of the Sun and the Goddess of Mother Earth, Pachamama, are both honored in this celebration mainly held within the atmospheric grounds of Sacsayhuamán, an Inca site just outside Cusco. See here for more on Peru's Incan sites away from Machu Picchu.