Egypt is a conservative, majority-Muslim country, and dressing with some awareness goes a long way — both for how you’re received and for practical comfort in the heat.
Shoulders and knees covered is the safe baseline for both men and women in most settings — loose, lightweight fabrics handle the heat far better than tight clothing anyway. Swimwear is fine at Red Sea resorts and pools but not appropriate walking through towns or at religious sites.
Women should bring a scarf to cover hair when required (most major mosques provide one, but having your own is more comfortable). Both men and women need to cover shoulders and legs; some sites also ask for covered arms.
Loose, lightweight fabric handles Egyptian heat better than tight clothing regardless of modesty norms.
Closed shoes for temple sites (uneven stone, hot sand) beat sandals despite the heat. A light scarf or shawl works double duty as sun protection and quick modesty coverage when moving between a beach resort and a temple visit on the same trip.
Tourist areas and resort zones are considerably more relaxed than rural towns — you won’t stand out for reasonable Western clothing in Cairo hotels or Red Sea resorts. The guidance above matters most at religious and heritage sites, and in smaller towns off the main tourist circuit.