The wet season properly starts in October and lasts through April, so it’s more prolonged than the dry period of the year. In Machu Picchu it coincides with the summertime, offering moderate temperatures during all seven rainy months. Precipitation level and the number of rainy days—that’s what changes.
In November Machu Picchu gets more damp, precipitation level grows up, and so does the number of the rainy days. But still the peak of rain season is yet to come. November is bearable so far if you can’t plan your vacation for any other time.
December, January, and February are the worst in terms of weather, and you should avoid travelling to Machu Picchu then. It’s the rainiest period of the year when precipitation level reaches its peak, and it rains every second day, if not more often. Late January and February are not simply the wettest months, but dangerous indeed, for heavy rainfalls may cause mudslides, and other troubles. However, if mudslides seem a minor problem for you, and you are looking for some extremal travelling experience, these months offers the best of white water rafting. Moreover, lots of fruits are available during this time of year.
March is still wet and warm, but summer starts winding up. Fruits are still in season, but soon it will be over. The same about white water rafting. March rains are not that heavy, as they were in February, and mudslides aren’t likely to happen, but still it isn’t the best time to visit Machu Picchu, for the surroundings are really damp, and many roads are still unavailable.
April marks a shifting period from wet, warm season to dry, and cool one. Air temperature decreases and rainfall is less abundant, yet it’s not the best time to visit Machu Picchu, the area still needs some time to drain up, so that all the tracks become crossable again. It’s worth waiting at least till mid-April. Cacao harvest starts in April and is going to proceed until August.