We've taken many precautions to protect Flash against elements like dust and rain. In fact, Flash is designed the meet the IP Rating Standards of IP 54.
So, what does that mean?
Do we recommend riding Flash through a monsoon? Nope.
Can you ride your bike home in the rain? Absolutely. When you get to your destination, bring the bike indoors, wipe it down with a dry towel, and you should be fine.