Large sandbar upwind. Semi-flatwater below it. The swell can be decent. Lots of space on the water. Don't ride directly upwind of the sandbar. There are many of unexposed stumps and branches right under the surface. Kite upwind into the channel or dwonwind into the flatwater of the Klickitat River mouth.
Weather in the summer can be 90+°F with water temperatures warm enough for boardshorts only in July and August. Shorties come in for June and September. Full wetsuits the rest of the year. Winters are not really kite-able here, with the bitter, blustering Easterly winds bringing snow, hail, and rain.
Spring: March to May, light winds 12-20, somewhat finicky. Summer: June to early September, windy, 15-35, pretty solid. Fall: September to October, light to moderate winds, but very steady: 13-25. The wind is usually gusty. Main direction westerlies. Works in NW, W, SW.
From Portland drive to Hood River and take the bridge over the river. Get onto 14 and drive east. Exit 14 and get to the sandbar at the river mouth of Klickitat River. Park in the lot on the north side of the road. Launch from the sandbar's southern most point.
Don't launch or ride directly upwind of the sandbar. There are many of unexposed stumps and branches right under the surface. Be careful when walking, there are some on the ground as well.