Rain can be discouraging. Even though most photographers know that bright sun is technically poor lighting for most purposes, sunny weather inspires one to get out and enjoy the day, while rain typically motivates one to find something of interest indoors. Even with a water-resistant camera, it is sometimes hard to muster enthusiasm when the weather is wet and grey.
Torrential downpours are not particularly photogenic, but light rain and drizzle can often create lovely mist effects for landscapes. Lacking a water-resistant camera, a home-made rain cover (such as shown last entry) can be employed to keep the fiddly electronics dry.
Another option is to shoot from under cover, out of a window or door. Open, covered structures such as parking garages are possibilities, although the available view may not be ideal. Shooting from an automobile offers a good deal of flexibility in view, but requires paying attention to avoid sprayed water from passing vehicles (shooting while driving is NOT recommended!)
Additional shooting opportunities occur just before or after the actual rainfall. The interplay of clouds and light can create dramatic lighting effects which typically appear and disappear quickly. Reflections in puddles offer the option of creative framing to show only a selected portion of the mirrored world.
The rain has to end eventually, so it is good to have a camera on hand, ready to shoot when it does.