Turning a window well into a greenhouse?

I have always been interested in plants, and today I was sitting in my room (in the basement) as it was raining. About a half hour later, the sun came out and water vapor began to condense on my window and the window well cover. Out of curiosity, I opened up the window, and it was pleasantly warm and really humid, even compared to outside. This made me wonder if it would be a viable area to grow plants? It gets sun pretty much all day, especially in the evening, and all of the plants inside would have ample access to water. Is this a good idea? Or would it fry them all? It gets to be about 10-15 degrees hotter than outside with the cover all the way on, but I can slide it off. Is