Storms moving through northern AZ today have dropped 6 inches of snow in some places including Jacob Lake on the North Rim of the GC. The forecast low tonight at the GCNP South Rim is 5 degrees.
These conditions shouldn't scare anyone and it is certainly not a reason to not visit the GCNP. But be advised and dress warmly including a hat and gloves and layers of clothing.
Be prepared for conditions like this at the GCNP from now until next April.