Water and electronics don't mix, so the first and most obvious challenge presented by taking photos of the rain is staying dry and keeping your camera from getting too wet. A few drops of water on the outside of the camera body won't ruin it, but you certainly don't want to expose your camera to a downpour (unless, of course, you own an underwater unit).
From a more technical standpoint, rainy weather can present difficult lighting and metering conditions, which can make it tough for even experienced photographers to take a photo with sharp focus. To make matters worse, the auto settings on most newer digital cameras will try to compensate for the dark conditions, adding too much light and making it look much brighter than it actually is. That's not necessarily what you want if you're trying to capture a photo of rain, so it's probably a good idea to turn off those automatic settings -- and leave them off [source: Fotoflock].
Flash photography in the rain can be frustrating for inexperienced photographers as well, because water will create a reflective surface on everything it comes into contact with. Given the conditions, the built-in flash on most cameras will produce too much light, creating a bright glare on the water.
Another reason that rain can be very difficult to capture in photographs is that falling rain is a moving object, and it can tend to blur, creating a dull, grey effect that is often very different from how the naked eye perceives rain [source: Fotoflock]. That can be a good thing if, for example, you're in a complete downpour and want to show sheets of rain that look more like a moving solid than individual raindrops. But if you want those raindrops to stand out, you'll have to make some adjustments, and we'll tell you how in the next section.