The cooler months from November to March are by far the best time, with warm, sunny days ideal for the beach, desert and sightseeing. Summer from June to September is extremely hot and humid, often above 42C, when outdoor activity is limited to early morning, evening and air-conditioned indoor attractions.
Summer heat and humidity are severe, and prolonged time outdoors can be dangerous. Stay hydrated, limit midday sun, use shade and air conditioning, and plan outdoor sights and the desert for the cooler months or the early and late hours.
Dubai is safe and welcoming but has laws and customs worth respecting. Dress modestly away from the beach and pools, avoid public displays of affection, do not drink alcohol outside licensed venues, and be discreet during Ramadan daylight hours.
Roads are wide and traffic moves fast, and jaywalking is both dangerous and fined. Cross only at designated crossings and signals, use the many pedestrian bridges and underpasses, and take extra care around fast multi-lane roads.