Will storing spices on the oven affect flavor or anything? The back of the oven is raised from the stove top and sits against the wall, forming a small shelf which is a very convenient location to store spices for use when cooking. Sitting there are things such as: garlic powder, paprika, basil, oregano, etc. in various plastic, glass, and metal containers they came in from the grocery store.

So, it turns out this area gets quite warm if the oven has been on for a bit, and I'm wondering if that will affect the spices sitting there?
I would keep them away from that area for 2 reasons - one is the heat, and second is that it's a dangerous location for the spices since the edge of most oven panels is generally very thin and not designed flat to be a shelf making it more likely for your spices to accidentally get knocked off than if you put them elsewhere.

Here is a link to a similar question answered by an expert: http://wiki.answers.com/Q/What_should_be_the_storage_temperature_for_spices