Best time to visit Valdez as for weather.
If you're going to be spending the summer in Alaska, you can do Valdez either early or late in the summer as you make the trip around the state. As a former resident of Valdez here's my opinion.
If you're not a fisherman, then visit it earlier in the summer. As a general statement, the earlier in the summer, the better - there will be less rain. It can actually be nice.
If you're a fisherman then you have to go when the fish are running which is mid to a little later in the summer. Usually after early July it starts raining more and more and more until snow starts in Sept or Oct.
Bill