It might be 3 hours free. I remember it being 2 hours free last summer.
We went twice on GRR on different days, both warm summer days. It was our first time on GRR. The first time we used the lockers and no one got very wet. The second time we said "why bother?" and skipped the lockers, and most of us (including me) got drenched. Go figure. In any case, no one cared about getting wet because of the weather and we were all in shorts. Nothing important got wet, but we did take steps to protect the tix, camera, etc.