The best time of day to hike Mount Vesuvius is during the early morning hours, ideally right when the park opens (usually around 9:00 AM). Hiking early allows you to avoid the intense midday Mediterranean sun, which can make the steep, dusty ascent much more grueling. Additionally, morning air is often clearer, providing sharper views of the Bay of Naples, the city of Pompeii, and the surrounding coastline before the afternoon haze sets in. Alternatively, a late afternoon hike can be spectacular for the golden hour light, but you must be very careful with the park's closing times, as they vary by season and the staff are strict about clearing the trails before dusk. Regardless of the time, it is essential to book your tickets online in advance, as there is no ticket office at the summit and mobile signal is notoriously unreliable on the volcano.