October through April is when I take most of my clients. The heat is manageable, the light in the morning is extraordinary — the low sun rakes across the relief carvings and you see detail that midday photographs flatten entirely. November is probably the peak: the Valley of the Kings is never what you'd call empty, but before 8am it is quiet enough that you can stand in a tomb chamber and hear yourself think.
December and January are popular with European and North American travelers, which means crowds at the cornerstones — Karnak, Valley of the Kings — peak between 9am and noon. I work around this. Most of my clients arrive at Karnak at 6:30am when it opens. By the time the tour groups are filing through the Hypostyle Hall, we are already at the Sacred Lake, or gone.
February and March are underrated. The weather is still excellent, there are fewer visitors than November or December, and the alfalfa fields between the Nile and the West Bank sites are green in a way that surprises people who expect only desert. Spring colors are not something you'll see on postcard versions of Luxor.
May through September is the heat season. Air-conditioned transfers and indoor-first itineraries make this workable, but it requires a different pace — earlier starts, longer midday rests, tombs before temples. I do take clients in summer. I was born here. The heat is not abstract to me — I know exactly when it becomes unfair, and I plan accordingly.
Ramadan changes Luxor in ways that are worth knowing about. Site opening hours may shift. Some restaurants are closed during daylight. But the evening atmosphere — the city after iftar — is something a standard itinerary doesn't include. If your dates fall during Ramadan and you want to experience it rather than work around it, tell me and I will build that in.