watering vanda on cloudy days

[Charles]

Let the plant tell you. First, it may like more sun. Longer periods and perhaps some shade. I know someone who uses 20% in Fl. I use 50% in Fl.
Then, watch the plant. You can go longer between waterings if the temp is not too high. You may not get the vigorous growth that some do, but you will have to settle for less than ideal conditions as your growing zone is 7.
As for the rainy days? If it is cool, I would rather not let mine get wet and sit too long. Especially the leaves. They do like to dry out faster and then get wet again later. Then dry in an hour.
Watch the plant. And watch for signs of trouble. Fungus and black spotting. Yellowing leaves (more than the bottom two at a time).
It's hard to make a fatal mistake before the plant tells you to stop except way too much sun too fast. Gradual exposure. Think strip tease. One step at a time.