That title statement is really aimed at photographers. Yes, I am serious. I can hear the questions going off..."Why?" you are asking. Ok, let me state my case for rooting for bad weather when you are traveling or on vacation (even if it's just for one day).
Bad weather creates interesting lighting
We have all witnessed the changing light or dimming of light that a storm can bring. This changing of light can be fantastic for a photographer. It can be very exciting to go out to shoot and see a storm rolling in and have that light change right in front of you. A city can be transformed and will look completely different in bad weather. Lights come on that you would normally only see at night and if you get lucky you might be at the forefront or tail end of the bad weather when you still have sunlight trying to break in. It's a different world when you are in bad weather and you can show what that world looks like through your camera when you go out and shoot in it.
Interesting reflections evolve through wet streets
If you are in a city or even a town, one of the best benefits to rain and bad weather is that a wet street is far more interesting than a dry one. A wet street will now reflect light (traffic lights, street lights, etc.). Couple that with the new interesting light that a storm brings translates into very interesting photos of an otherwise mundane scene.
No crowds to deal with
One of the worst things about trying to take great photos while you are traveling can be other tourists getting in your way. When bad weather hits it drives away the crowds. Now you have the whole playground to yourself. I personally love trying to capture a city or a scene without too many people walking through the scene. There can be a time and place for that, but if you like the solitude of shooting without people getting in the way you can get up super early to take photos, stay up late (which isn't a guarantee that you won't have more people in your photos), or go out in bad weather.
Drama in the sky = a cooler photo
One of the top reasons why I like to go out in bad weather to shoot is the drama in the sky. I am a huge believer that a great sky can help take an good photo to the next level. A storm rolling in can make an average landscape photo a phenomenal one.
Yes, there is a risk of taking your camera out in the rain. I still get clammy hands when I do shoot in the rain. A simple plastic grocery bag can protect a DSLR camera with a zoom lens on it.
Poke or cut a hole at the closed end of the bag and place your camera through the large end and stick your lens through the cut hole. Then just use a good rubber band to secure the end of the bag to your lens. Also having an umbrella helps too.
Next time it rains when you are traveling or even if you are at home. Take the camera, head out and explore. I am positive you will end up with some interesting photos.