I wouldn't store any wood in an attic. You don't really have to worry about temperature range. What you need to take into account are moisture, ventilation and flat surface.
Even though your attic appears dry it's not. The humidity levels fluctuate significantly in a non-climate controlled attic. That alone is reason enough to rule out attic storage, not to mention proper ventilation.--
Stop The Mindless Killings Stop Over Fishing