We live in a new home (less than two years old) and when it is windy I notice a horrible smell coming from the master bath. I can not locate where the smell is coming from (like the toilet, sink, shower or tub) the whole bathroom just smells. We are not on a septic tank, just the city sewer. I have also noticed that the toilet gets a mold growing on the inside of the bowl despite frequent cleanings.

The mold in the toilet and that smell are unrelated. The smell is likley a poorly installed wax ring under the toilet. If the home is still under warranty have their plumber replace the ring or at least check out the problem. If the warranty is over you can come back here and several of us can help you replace the ring. Back to the mold for a moment. Mold spore are pretty much everywhere and will start to grow 12-24 hours after they get wet. However I have not seen mold grow in an actively used toilet. Are you sure its mold or just a stain/ring.