Photography is all about quality of light, and weather conditions dramatically change the appearance of all buildings, both indoors and out. So before you ever begin shooting, consider the clouds.
If you're trotting across the globe for your shoot, you'll want to begin by checking average weather conditions for your destination. Hitting New Orleans in August? Prepare for monsoon season, with heavy, intermittent rain followed by blue skies full of enormous, puffy clouds. Winnipeg in December? Be ready for snow.
Varying degrees of cloud cover, precipitation and sun change architecture's appearance in profound ways. Hard sunlight can create strong contrast, bringing out lines and patterns. An overcast day, though, diffuses light, softens edges and reveals colors and tones that strong light might overpower. And rain can add a glossy sheen to all sorts of construction materials.
Outdoor light matters for indoor photography, too. On a sunny day, you might see lovely streaks of light strewn throughout a building that on cloudier afternoons seems dank and unwelcoming. Or, you might find yourself wishing for a few clouds so that you can capture more even, smooth lighting inside a quiet chapel.
Remember that light is a changeable thing. It can be boring or magical depending on the minute, and the only way to find the best light for a subject is to experiment repeatedly.