Het weer in Aguas Calientes (Machu Picchu) in december

Forum posters are consistent that December sits right at the start of the wet season (December through February are the wettest months), so a mostly-overcast, roughly 50%-chance-of-rain-on-any-given-day pattern is the norm rather than the exception. The typical shape of a December day: some rain for a couple of hours in the morning or afternoon, then clearing to sun, with an all-day washout called unlikely even if grey skies are close to guaranteed. Daytime highs run cool-ish (60sF) with lows dropping into the high 40sF, and a proper rain jacket plus shoes with good grip are treated as essential packing rather than optional given the regularly slick trail and cobblestone conditions this time of year.

Aguas Calientes-forum threads on rain describe February as genuinely the wettest month locally, posters calling the odds of a fully clear visit low though not impossible. Regulars describe one visitor's January-into-February stretch as mostly cloudy with regular overnight showers rather than sustained daytime downpours, a high-probability forecast not matching the actual experience. Posters call some sun typical most days despite the wetter reputation, a full washout less common than the forecast alone suggests. Regulars recommend a backup plan given the train's bimodal service, passengers sometimes switching between bus and train at Ollantaytambo depending on tracks. Posters recommend staying overnight in town for at least one night, a second shot at the ruins if the first day disappoints. Regulars call real waterproof layers non-negotiable. The record: 20.7C days feeling like 23C, 14.8C nights, an extraordinarily high 305.6mm across over 28 days and 90 percent humidity.

Aguas Calientes-forum threads on weather around Cusco and Machu Picchu describe March as still within the wetter season though rarely an all-day washout, posters calling a typical pattern partly cloudy mornings, pleasant daytime conditions, then a shower in the afternoon or overnight. Regulars call March genuinely more unpredictable than May, though a full day lost to weather is uncommon. Posters describe a passing shower as usually lasting an hour or two before clearing, skies opening back up to real sun. Regulars recommend a proper poncho or rain shell regardless of the morning, conditions shifting fast with elevation and time of day. Posters call one Inca Trail trekker's report of sunny days and only overnight showers fairly typical for this stretch. Regulars recommend layering for the daily range, warm gear still useful with daytime warmth. The record: 20.7C days feeling like 23C, 14.6C nights, an extraordinarily high 296.1mm across nearly 31 days and 90 percent humidity.

Aguas Calientes-forum threads on April conditions confirm real rain remains a genuine possibility even this late, the broader wet season typically running into early April before conditions properly settle. Posters call early April considerably cloudier and wetter than the back half of the month, the shift toward more reliable weather usually not complete until closer to May. Regulars describe forecasts here as genuinely unreliable, several posters recommending packing for any outcome rather than trusting a specific prediction. Posters call a light rain jacket standing advice for the Machu Picchu visit, a shower entirely possible on an otherwise promising morning. Regulars recommend bringing water from town rather than buying it at the site, prices considerably higher there. Posters call the ruins worth visiting regardless of the sky. The record: 20.7C days feeling like a punishing 23C, 14.1C nights, an extraordinarily high 183.1mm across nearly 29 days and 89 percent humidity.

Aguas Calientes-forum threads on September Machu Picchu trips describe genuinely mixed real-world experience, some posters reporting blue skies and full sun while another specifically recalled a forecast calling for showers and thunderstorms that never materialized. Regulars call daytime conditions comfortable enough for a t-shirt, though nights turn genuinely cold, a proper warm coat standing advice regardless of how mild the day felt. Posters recommend a real layering system for the climb, trail pants and a base layer paired with a lightweight fleece and waterproof shell to cover the full range of conditions possible in a single day. A light poncho is worth packing even on a promising morning, showers here capable of arriving with little warning. Regulars recommend carrying water bought in town given how expensive it runs once up at the site. The record: 20.8C days feeling like 21C, 12.8C nights, an extraordinarily high 214mm across nearly 24 days and 84 percent humidity.