The first 50m are usually very shallow. You should walk out. Then there is enough space until you will hit a reef after approx. 500-800m. You can stand in a lot areas. The water is waist deep. If you have green water below you, then it is deep enough to jump. Avoid dark/blue spots in the green water. This could be a shallow rock/reef, but they are easy to spot. Best is to stay upwind of the flat area. Then you have a safety zone if your kite drops and can't be launched any more. Water is flat to choppy, depending on the wind situation. You will be the only kiteboarder on the water. There is no windsurfing, no kiteboarding.
You have enough space on the beach. Please don't park your car or set up your kite near other Arabic people. Everybody
here needs his private room on the beach. Please respect this. If you are lucky you will find a few Arabic people who speak a little bit English. They could help you launch or catch the kite. Better and safer is a buddy who helps you. Expect a big crowd watching you enthusiastic. A lot bypassers will stop and cheer you. The beach could be cleaner. There is some garbage at the beach.
Don't kiteboard "nearly naked". I did wear kite trousers. You can use a short wetsuit, but it's also possible without wet suit. Only with lycra. Depends on your personal preferences.
Wind increases thermally in the early afternoon. Best month are December to February. You can expect 14-28 knots. All wind information on the web shows 3-5 knots less than you will have actually! Wind is pretty steady.
Don't expect a lot signs. Don't follow any sign, which says "Corniche". This will most probably not be the "South Corniche"! There are a lot Corniches in Jeddah! Driving in Jeddah is bit difficult. You have to find King Faisal Rd. Go south on King Fahd Rd which converts to the freeway, take exit Television Street. Make a U-Turn, then don't drive again on the freeway. Stay right. Next left will be King Faisal Rd (GPS Waypoint N 21 27' 33.2"; E039 11' 30.4). There you will see the first sign "South Corniche". This is the beach area. Follow the road, keep straight or right, passing a Hyper Market on the left side, continue to GPS Waypoint (N 21 19' 47.0"; E 039 11' 27,3 "). This is a manned military checkpoint, pass slowly, turn immediately right and follow the road 20 km (after 15 km you will see a small fishermen harbour). There is the beach (at GPS Waypoint (N 21 14' 02,7"; E039 08' 42,9"). Other beaches are further south (approx. 13km). Also north of Jeddah should be a beach. The call it North Coast. The problem is, that the road is far from the water and all beach roads are guarded by life guards. It's not sure that they will let you pass.