Condensation is produced when warm air meets cold air. It happens when you leave your refrigerator open on hot days, and it can happen if you open your hot oven up on a particularly cold day. Even the act of cooking food will produce some amount of condensation from the steam. You can expect some droplets when baking water-laden items like tomatoes. However, an oven is not an appliance that typically plays well with moisture. Excessive condensation can cause premature rust and damage some of the heat-producing parts. If you experience condensation that is more than a droplet or two of moisture without an explanation, here is what to look for in order to fix it.
In order to keep the warm air inside the oven, your oven door actually has two seals. There is the pliable, heat-resistant fabric seal that runs alongside the edge of the door and there is a window seal that runs around the edge of your oven window. If either fails, it can result in condensation as the warm air escapes. Typically, you will see that condensation on the glass if it is the window seal and on the door if it is the door seal.
Not every oven has one, but if your oven has a tangential fan that blows cool air over the exterior of the oven to keep it a manageable temperature it can go faulty. If you do and it appears to not work — something you can tell by the lack of sound — then this can be the cause. The fan can keep condensation at bay, but if it is not working, then it obviously cannot do its job.
Your Room is Too Cold
If your oven produces condensation often, but really only in the winter, you simply need to turn your heat up in your home. Usually the temperature in which condensation is produced is really too cold for comfort, but if you occasionally use your oven to both bake and heat the kitchen, it can happen.