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
A quote from the below link for herbs;
"Storing Dried Herbs
1.Store your dried herbs in air tight containers. Zip closing bags will do. I like to use small canning jars.
2.Be sure to label and date your containers.
3.Your herbs will retain more flavor if you store the leaves whole and crush them when you are ready to use them.
4.Discard any dried herbs that show the slightest sign of mold.
5.Place containers in a cool, dry place away from sunlight.
6.Dried herbs are best used within a year. As your herbs lose their color, they are also losing their flavor.
7.Use about 1 teaspoon crumbled dried leaves in place of a tablespoon of fresh"
http://gardening.about.com/od/vegetablepatch/a/DryingHerbs.htm
Once opened, many spices have a fairly short shelf life in any case. Most people keep herbs and spices, and continue to use them, long after their flavour has been lost.
I would suggest buying herbs and spices in very small quantities, such that you would expect to buy more every couple of months or so. It works out more expensive this way, but you know that the spices you are using actually taste of something more than dust.
With that regime in place, it should be OK for the spices to have occasional warm spells from heat escaping from your oven. Do make sure that the shelf is actually a safe surface.
