It would be best to get it back on as soon as possible. Espec where you are, the lower engine bay covers can help keep mud, snow, excess water from getting into the engine bay. It also does add some (mostly sacrificial) protection to the lower parts of your engine (read: oil pan). Likely worth it in the long run.
I was also thinking that it might change the engine noise (it was actually called a sound dampening pan on my VW).